shell and tube

INSTRUCTION MANUAL

HT33

SHELL AND TUBE HEAT EXCHANGER

HT33

ISSUE 10

NOVEMBER 2004

THIS INSTRUCTION MANUAL SHOULD BE USED

IN CONJUNCTION WITH THE MANUAL SUPPLIED WITH THE

HT30X or HT30XC HEAT EXCHANGER SERVICE UNIT

This Manual provides the necessary information for operating the equipment in conjunction with the HT30X or HT30XC Service Unit, and for performing a

range of Teaching Exercises designed to demonstrate the basic principles of Heat Exchanger theory and use.

IMPORTANT SAFETY INFORMATION All practical work areas and laboratories should be covered by local safety regulations which must be followed at all times. If required Armfield can supply a typical set of standard laboratory safety rules.

Your HT33 Shell and Tube Heat Exchanger has been designed to be safe in use, when installed, operated and maintained in accordance with the instructions in this manual. As with any piece of sophisticated equipment, dangers may exist if the equipment is misused, mishandled or badly maintained.

Electrical Safety The equipment described in this Instruction Manual operates from a mains voltage electrical supply. It must be connected to a supply of the same frequency and voltage as marked on the equipment or the mains lead. If in doubt, consult a qualified electrician or contact Armfield.

The equipment must not be operated with any of the panels removed. Refer to the HT30X/HT30XC Heat Exchanger Service Unit for information on the use and testing of the Residual Current Device included as a safety measure on the service unit.

Hot Surfaces and Liquids The heat exchanger is capable of producing temperatures that could cause burns. Do not touch the heat exchanger while it is in operation and allow sufficient time for it to cool after use before handling the exchanger or pipework. If the model needs to be changed it should be handled by the white base on which the exchanger is mounted. Do not open the circulator unit on the service unit except in accordance with the safety instructions included in the HT30X/HT30XC Heat Exchanger Service Unit product manual.

Waterborne Hazards The equipment described in this instruction manual involves the use of water, which under certain conditions can create a health hazard due to infection by harmful micro-organisms.

For example, the microscopic bacterium called Legionella pneumophila will feed on any scale, rust, algae or sludge in water and will breed rapidly if the temperature of water is between 20 and 45C. If water containing this bacterium is sprayed or splashed, the air-borne droplets created can transmit a form of pneumonia called Legionnaires Disease, which is potentially fatal.

Legionella is not the only harmful micro-organism which can infect water, but it serves as a useful example of the need for cleanliness.

Under the COSHH regulations, the following precautions must be observed:-

Any water contained within the product must not be allowed to stagnate, i.e. the water must be changed regularly.

Any rust, sludge, scale or algae on which micro-organisms can feed must be removed regularly, i.e. the equipment must be cleaned regularly.

Where practicable the water should be maintained at a temperature below 20C. If this is not practicable then the water should be disinfected if it is safe and appropriate to do so. Note that other hazards may exist in the handling of biocides used to disinfect the water.

A scheme should be prepared for preventing or controlling the risk incorporating all of the actions listed above.

Further details on preventing infection are contained in the publication The Control of Legionellosis including Legionnaires Disease - Health and Safety Series booklet HS (G) 70.

ARMFIELD LIMITED

OPERATING INSTRUCTIONS AND EXPERIMENTS

HT33 SHELL AND TUBE HEAT EXCHANGER

PAGE NO.

1 INTRODUCTION 1-1

2 DESCRIPTION 2-1

3 OPERATIONAL PROCEDURES 3-1

3.1 Priming the hot water circuit ................................................................... 3-1

3.2 Setting the cold water flow rate ............................................................... 3-2

3.3 Setting the hot water temperature ............................................................ 3-3

3.4 Effect of cold water temperature on heat exchange................................. 3-5

3.5 Operation of Guest push fittings .............................................................. 3-6

4 ROUTINE MAINTENANCE 4-1

5 NOMENCLATURE FOR HT33 5-1

6 REFERENCE TABLES 6-1

6.1 Table 1: Specific Heat Capacity of Water (Cp kJ/kgK) ........................ 6-1

6.2 Table 2: Density of Water ( kg/m3) ....................................................... 6-1

7 INDEX TO PRACTICAL TRAINING EXERCISES 7-3

7.1 Practical Training Exercise HT33A......................................................... 7-5

7.2 Practical Training Exercise HT33B......................................................... 7-8

7.3 Practical Training Exercise HT33C....................................................... 7-11

7.4 Practical Training Exercise HT33D....................................................... 7-17

7.5 Practical Training Exercise HT33E ....................................................... 7-21

7.6 Practical Training Exercise HT33F ....................................................... 7-26

7.7 Exercise HT33G: Project Work ............................................................. 7-31

8 Appendix A: Installation Guide 8-1

1 INTRODUCTION

This instruction manual describes the operation of the HT33 Shell and Tube Heat Exchanger which must be used in conjunction with the HT30X or HT30XC Heat Exchanger Service Unit (supplied separately). Details of the service unit are given in a separate instruction manual, which is supplied with the unit. The service unit provides the hot and cold water streams for the heat exchanger along with flow and temperature measurement and control and the facility for computerised data logging of the results.

The HT33 Shell and Tube Heat Exchanger is one model in a range of heat exchangers designed for use with the HT30X/HT30XC service unit. A full description of the exchanger is provided in the DESCRIPTION section of this manual (page 2-1). Other heat exchangers available in the range include the HT31 Tubular, HT32 Plate, the HT34 Jacketed Vessel with Coil and Stirrer, the HT36 Extended Tubular and HT37 Extended Plate with Regeneration. These modules are interchangeable on the service unit and each come with their own product manual.


1-1

2 DESCRIPTION

The shell and tube heat exchanger is commonly used in the food and chemical process industries. This type of exchanger consists of a number of tubes in parallel enclosed in a cylindrical shell. Heat is transferred between one fluid flowing through the tubes and another fluid flowing through the cylindrical shell around the tubes.

In this miniature exchanger, baffles inside the shell increase the velocity of the fluid and hence the rate of heat transfer. The exchanger has one shell and seven tubes with two transverse baffles in the shell.

The exchanger is mounted on a PVC base plate which incorporates four holes, which locate it on four studs at the left hand end of the HT30X/HT30XC service unit. The PVC base plate is secured to the service unit using thumb nuts.

In normal operation the hot fluid from the hot water circulator enters the header at one end of the shell and passes through the bundle of stainless steel tubes.

The cold fluid from the cold water supply passes through the cylindrical shell. This arrangement minimises heat loss from the exchanger without the need for additional insulation and allows the construction of the exchanger to be viewed.

The outer annulus, caps and baffles are constructed from clear acrylic to allow visualisation of the heat exchanger construction and minimise thermal losses. These provide a liquid seal, accommodate differential expansion between the metal and plastic parts and allow the inner metal tubes to be removed for cleaning.

O ring seals allow differential expansion between the metal and plastic parts and allow the inner metal tubes to be removed for cleaning. The end housings incorporate the necessary fittings for sensors to measure the fluid temperatures and connections to the hot and cold water supplies.

2-1

The four thermocouple temperature sensors are labelled T1 to T4 for identification and each lead is terminated with a miniature thermocouple plug for connection to the appropriate socket on the side of the left hand side of the console on the service unit.

A length of flexible tubing is attached to each fluid inlet/outlet, terminated with a ferrule. This allows rapid connection to the appropriate fittings on the HT30X/HT30XC service unit, and conversion from countercurrent to cocurrent operation (the direction of water flow can be changed by reversing the appropriate connections). The fittings on the HT30X/HT30XC service unit and HT33 are colour coded red for hot water and blue for cold water to aid identification.

Red Blue

Details of the connections are given in the Specifications and Operational Procedures sections of this manual, and in the Installation Guide (Appendix A in this manual).

2-2


3 OPERATIONAL PROCEDURES

Before operating the equipment, ensure that the HT33 Heat Exchanger and the HT30X/HT30XC base unit have been assembled and installed as shown in the Installation Guide (Appendix A).

3.1 Priming the hot water circuit

(If using the older HT30X instead of the HT30XC, refer to the HT30X manual Operational Procedures section for the correct method of priming the hot water circuit, instead of using these instructions)

Remove the lid from the hot water vessel. Fill the vessel by pouring clean (preferably demineralised) water through the perforated screen until the level is approximately 20 mm from the top.

Check that the low-level indication in the software is not activated.

Check that the in-line isolating valves are both fully open.

Set the pump speed to 50% in the software and run the pump using counter-current operation until all air bubbles are displaced from the flexible tubing into the hot water vessel.

Top up the level of this vessel as necessary to maintain the level above the tip of the level electrode (typically 20 mm from the top of the vessel).

3-1


If air bubbles remain in the flexible tubing increase the pump speed or squeeze the tubing to displace them.

Note: Counter-current operation should always be selected when priming the hot water side of a heat exchanger for the first time.

3.2 Setting the cold water flow rate

(If using the older HT30X instead of the HT30XC, refer to the HT30X manual Operational Procedures section for the correct method of setting the cold water flow rate, instead of using these instructions)

The Cold Water Flow Valve can be controlled from the computer software. The valve can be driven from 0% (fully closed), to 100% (fully open) in steps of 1%.

The actual flow rate achieved at any particular setting will be dependent on the water supply pressure, the pressure regulator setting, and the losses through the particular heat exchanger in use. This flow rate is measured by a flow meter and displayed in litres/min on the computer screen.

In normal use, the valve setting is adjusted until the desired flow rate is achieved.

Setting the hot water flow rate and direction

The hot water flow rate can be controlled from the computer software by varying the rotational speed of the re-circulation pump.

Again this can be set from 0% to 100%, with the actual flow rate being measured by a flow meter and displayed in L/min on the computer screen.

The hot water flow direction is set as a default value in the Armfield Software. If a counter-current exercise is chosen, the flow is in the direction indicated by the arrows

3-2


adjacent to the two hot water connections. If a co-current exercise is chosen the direction of rotation of the pump and therefore the flow of water is reversed.

Note: A change in the temperature of the water will affect the viscosity of the water resulting in a small change in flowrate. It will therefore be necessary to adjust the hot water flow control in the software if it is required to perform tests at the same flowrate but different temperatures.

3.3 Setting the hot water flow rate and direction

(If using the older HT30X instead of the HT30XC please refer to the HT30X manual Operational Procedures section for the correct method of setting the hot water flow rate and direction, instead of using these instructions. Cocurrent or countercurrent flow is set by manually changing the plumbing of the HT30X, and cannot be controlled from the computer software)

The hot water flow rate can be controlled from the computer software by varying the rotational speed of the re-circulation pump.

Again this can be set from 0% to 100%, with the actual flow rate being measured by a flow meter and displayed in L/min on the computer screen.

The hot water flow direction is set as a default value in the Armfield Software. If a counter-current exercise is chosen, the flow is in the direction indicated by the arrows adjacent to the two hot water connections. If a co-current exercise is chosen the direction of rotation of the pump and therefore the flow of water is reversed.

Note: A change in the temperature of the water will affect the viscosity of the water resulting in a small change in flowrate. It will therefore be necessary to adjust the hot water flow control in the software if it is required to perform tests at the same flowrate but different temperatures.

3.4 Setting the hot water temperature

(If using the older HT30X instead of the HT30XC, refer to the HT30X manual Operational Procedures section for the correct method of setting the hot water temperature, instead of using these instructions)

Two modes are available for controlling the hot water temperature, a manual (or open loop) control mode to provide constant heater power and an auto (or closed loop) temperature control mode. Both modes are accessed via the software.

3-3


To access the heater control mode click the software control button close to the appropriate sensor.

In manual mode, the heaters (SSR Drive) are set to be on for a fixed proportion of time, operator selectable from 0% to 100%. This mode is useful when assessing energy balances or settling times.

In auto mode, the power to the heaters is modulated in accordance with a PID algorithm to achieve a stable temperature at one of the sensors (usually the hot water inlet to the heat exchanger). Advanced users may change the P, I and D parameters to perform process control investigations.

3.5 Measuring the water temperatures and flow rates

(If using the older HT30X instead of the HT30XC, and not using the HT30X software, then refer to the HT30X manual Operational Procedures section for the correct method of measuring the water temperatures and flow rates instead of using these instructions)

The temperature of the hot and cold fluids at the fluid inlet and outlet are measured using type k thermocouples. The outputs from these sensors are displayed on the software mimic diagram screen, calibrated in C. Sensor outputs may be monitored in X-Y graph format in real time by selecting the icon or bar graph format by selecting the icon. A snapshot of the sensor outputs may also be sent to a results

3-4


table by selecting the icon and plotted on a graph via the icon, and may then be saved in native .vts format for later reference within the Armfield software, or exported in another spreadsheet format such as Microsoft Excel (not provided by Armfield).

The hot and cold flow rates are monitored using turbine-type flow sensors, calibrated in litres per minute. The outputs from these sensors may be monitored, logged and saved as for the temperature sensor outputs.

3.6 Effect of cold water temperature on heat exchange

The temperature of the water entering the equipment from the mains cold water supply will affect the range of range of hot and cold water flowrates and/or the temperature of the hot water that can be achieved when using the equipment.

The heater in the hot water circulator has a nominal rating of 2 kW, limiting the heat exchange from the hot water stream to the cold water stream to this value. If the temperature of the hot water will not reach the value set on the PID controller with the controller providing full power to the heater then this indicates that the limit of the heater power has been reached. This is not a problem and simply requires an adjustment to the settings on the equipment.

To operate with the same flowrates then a lower hot water temperature must be accepted (reduced differential temperature between the two fluid streams). To operate with an elevated hot water temperature then one or both of the flowrates must be reduced until the demand on the heater is less than 2 kW.

Some of the settings in the practical training exercises may be affected in this way. An excessively warm mains water supply will not present any problems since the temperature difference between the two fluid streams will be reduced. This would allow the hot water stream to be increased to even higher temperatures than quoted. An excessively cold mains water supply may mean that the hot water temperature quoted cannot be achieved because of the increased temperature difference between the two fluid streams. Operation at reduced hot water temperature or reduced flowrate must then be accepted.

3-5


3.7 Operation of Guest push fittings

Guest push fittings are used on the equipment for convenience when changing the configuration or removing items for cleaning. The diagrams below show the simple operation of these fittings:-

To connect to a quick release fitting

Align the parallel section of the rigid tube with the loose collet on the quick release fitting

and push firmly until the tube stops.

An 'O' ring inside the fitting provides a leak-proof seal between the tube and the fitting. The collet grips the tube and prevents it from being pulled out from the fitting.

To disconnect from a quick release fitting

Push the loose collet against the body of the quick release fitting while pulling the tube firmly.

The tube will slide out from the fitting. The tube/fitting can be assembled and disassembled repeatedly without damage.

3-6


3.8 Connections to the I/O data port on HT30X

To allow access to the measurement signals in applications from the HT30X, other than when using an Armfield interface device, the connections to the 50 way connector are listed below for information:-

PIN NO CHANNEL NO SIGNAL FUNCTION Analog Inputs (0-5Vdc): 1 Ch 0 signal Temperatures 1 to 4 via analog switch (0-200C) 2 Ch 0 return 3 Ch 1 signal Hot water flow Fhot (0-3 L/min) 4 Ch 1 return 5 Ch 2 signal Cold water flow (0-3 L/min) 6 Ch 2 return 7-21 Not used Analog Outputs (0-5Vdc): 22-25 Not used Digital Inputs ( 0/5 Vdc): 26-37 Not used Digital Outputs (0/5 Vdc): 38 Ch 0 Analog switch 39 Ch 1 Analog switch 40 Ch 2 Analog switch 41 Ch 3 Analog switch 42 Digital ground 43 Ch 4 Inhibit analog switch 44-46 Not used 47 Digital ground 48-50 Not used

3-7


3.9 Connections to the USB port on HT30XC

To allow access to the measurement signals in applications other than the Armfield software when using the HT30XC, Armfield have provided a USB driver with the software installation disk. Armfield does not provide alternative software or instructions on using alternative software. The channel numbers for the USB port are listed below:-

CHANNEL NO SIGNAL FUNCTION Analog Inputs (0-5Vdc): Ch 0 signal Temperatures 1 to 4 via analog switch (0-133C) Ch 0 return Ch 1 signal Hot water flow Fhot (0-5 L/min) Ch 1 return Ch 2 signal Cold water flow (0-5 L/min) Ch 2 return Not used Analog Outputs (0-5Vdc): Not used Digital Inputs ( 0/5 Vdc): Not used Digital Outputs (0/5 Vdc): Ch 0 Analog switch Ch 1 Analog switch Ch 2 Analog switch Ch 3 Analog switch Digital ground Ch 4 Inhibit analog switch Not used Digital ground Not used

3-8


4 ROUTINE MAINTENANCE

To preserve the life and efficient operation of the equipment it is important that the equipment is properly maintained. Regular servicing/maintenance of the equipment is the responsibility of the end user and must be performed by qualified personnel who understand the operation of the equipment.

In addition to regular maintenance the following notes should be observed:-

1. The HT30X/HT30XC service unit should be disconnected from the electrical and water supplies when not in use.

2. Water should be drained from the inner tubes and outer annulus of the HT33 heat exchanger after use to minimise build up of scale or fouling on the heat exchange surfaces.

The water can be drained by simply disconnecting the four flexible tubes connecting the exchanger to the HT30X/HT30XC service unit.

3. Any build up of scale inside the heat exchanger can be removed by passing a mild descaler through the exchanger then flushing thoroughly with clean water.

Any stubborn deposits can be eliminated by manual cleaning having carefully removed the inner tube from the outer annulus. To remove the metal tube for cleaning, disconnect the quick release fittings from each end of the metal tube then pull the tube out of the assembly taking care not to damage the 'O' ring seals. After cleaning, lubricate the 'O' ring seals with a small amount of wetting agent before re-inserting the metal tube and replacing the quick release fittings.

Note: The PVC housing at each end of the acrylic tube is bonded to the acrylic tube and cannot be removed.

If it is necessary to replace the 'O' ring seals the replacements should have the following specification:

Material Nitrile rubber Diameter To suit 3/8" shaft Section 0.103" section

For reference the Dowty part number is 200-110-4470

4-1


5 NOMENCLATURE FOR HT33

Name Symbol SI unit ID of tube di m OD of tube do m Arithmetic mean diameter of tube dm m Heat transmission length L m Heat transfer area A m2 Specific Heat Capacity hot fluid Cphot kJ/kgK Specific Heat Capacity cold fluid Cpcold kJ/kgK Hot fluid inlet temperature T1 C Hot fluid outlet temperature T2 C Cold fluid inlet temperature T3 C Cold fluid outlet temperature T4 C Decrease in hot fluid temperature thot C Increase in cold fluid temperature tcold C Driving force, hot fluid inlet t1 C Driving force, hot fluid outlet t2 C Logarithmic Mean Temperature Difference tlm C Volume flowrate (hot fluid) qvhot m3/s Volume flowrate (cold fluid) qvcold m3/s Density of hot fluid hot kg/m3

Density of cold fluid cold kg/m3

Mass flow rate hot fluid qmhot kg/s Mass flow rate cold fluid qmcold kg/s Heat power emitted from hot fluid Qe W Heat power absorbed by cold fluid Qa W Heat power lost (or gained) Qf W Overall Efficiency % Temperature Efficiency hot fluid hot % Temperature Efficiency cold fluid cold % Mean Temperature Efficiency mean % Overall Heat Transfer Coefficient U W/m2C

5-1


6 REFERENCE TABLES

6.1 Table 1: Specific Heat Capacity of Water (Cp kJ/kgK)

C 0 1 2 3 4 5 6 7 8 9 0 10 20 30 40 50 60 70

4.1274

4.1919

4.1816

4.1782

4.1783

4.1804

4.1841

4.1893

4.2138

4.1904

4.1810

4.1781

4.1784

4.1807

4.1846

4.1899

4.2104

4.1890

4.1805

4.1780

4.1786

4.1811

4.1850

4.1905

4.2074

4.1877

4.1801

4.1780

4.1788

4.1814

4.1855

4.1912

4.2045

4.1866

4.1797

4.1779

4.1789

4.1817

4.1860

4.1918

4.2019

4.1855

4.1793

4.1779

4.1792

4.1821

4.1865

4.1925

4.1996

4.1846

4.1790

4.1780

4.1794

4.1825

4.1871

4.1932

4.1974

4.1837

4.1787

4.1780

4.1796

4.1829

4.1876

4.1939

4.1954

4.1829

4.1785

4.1781

4.1799

4.1833

4.1882

4.1946

4.1936

4.1822

4.1783

4.1782

4.1801

4.1837

4.1887

4.1954

6.2 Table 2: Density of Water ( kg/m3)

C 0 2 4 6 8

0

10

20

30

40

50

60

70

999.8

999.7

998.2

995.7

992.2

988.0

983.2

977.8

999.9

999.5

997.8

995.0

991.4

987.1

982.2

976.6

999.9

999.2

997.3

994.4

990.6

986.2

981.1

975.4

999.9

998.9

996.8

993.7

989.8

985.2

980.0

974.2

999.9

998.6

996.2

993.0

988.9

984.2

978.9

973.0

6-1


6-2


7 INDEX TO PRACTICAL TRAINING EXERCISES

HT33A: Fluid to Fluid Heat Transfer 7-5

HT33B: Energy Balance and Overall Efficiency 7-8

HT33C: Cocurrent and Countercurrent Flow 7-11

HT33D: Overall Heat Transfer Coefficient 7-17

HT33E: Effect of Flow Rate 7-21

HT33F: Driving Force 7-26

HT33G: Project Work 7-31

7-3


7-4


7.1 Practical Training Exercise HT33A

Objective To demonstrate indirect heating or cooling by transfer of heat from one fluid

stream to another when separated by a solid wall (fluid to fluid heat transfer)

Method By measuring the changes in temperature of two separate streams of water

flowing through the inner tube bundle and outer shell of a shell and tube heat exchanger

Equipment Required HT30X/HT30XC Heat Exchanger Service Unit

HT33 Shell and Tube Heat Exchanger

Equipment set-up Before proceeding with the exercise ensure that the equipment has been set up and the accessory installed as described in this manual, with a cold water supply connected and the pressure regulator adjusted. The apparatus should be switched on, and if using the HT30XC the service unit should be connected to a suitable PC on which the software has been installed. Computer operation is optional with the HT30X.

Prime the hot and cold water circuits using the cold water supply (Refer to the Operational Procedures on page 3-1 if you need details on how to prime the equipment).

If using the HT30XC, or the HT30X with the optional software, run the HT33 software for the service unit used (HT30XC software must be used with the HT30XC and HT30X software with the HT30X, as the calibration for the sensors differs between the two service units). If using the HT30XC, select the Countercurrent exercise. If using the HT30X, select Exercise A and then select Countercurrent Operation on the software display option box.

Theory/Background Any temperature difference across the metal tube wall will result in the

transfer of heat between the two fluid streams. The hot water flowing through the inner tube bundle will be cooled and the cold water flowing through the outer shell will be heated.

Note: For this demonstration the heat exchanger is configured with the two streams flowing in opposite directions (countercurrent flow). The cold fluid flowing through the shell is forced to flow over and under baffles

7-5


in the shell which force the fluid to flow across the tube bundle to improve the heat exchange.

Procedure (Refer to the Operational Procedures on page 3-1 if you need details of the instrumentation and how to operate it. The mains supply should be switched on before starting this experiment.)

Set the temperature controller to 60C. If using the HT30X then switch on the hot water circulator.

Adjust the cold water control valve setting to give a cold water flow rate of 1 litre/min.

If using HT30X, adjust the hot water control valve setting Vhot to give a hot water flow of 3 litres/min. If using HT30XC, click on the button for the hot water flow rate controller, set the controller to Automatic and enter a Set Point value of 3 litres/min. Apply and click OK.

Allow the temperatures to stabilise (monitor the temperatures using the sensor display on the software screen or control console).

When the temperatures are stable select the icon to record the following, or manually note the values: T1, T2, T3, T4, Fhot, Fcold.

Adjust the cold water control valve to give 2 litres/min.

Allow the heat exchanger to stabilise then repeat the above readings.

If using the software, save the logged data by selecting Save or Save As from the File menu. Browse to the location you wish to place the saved data and give the results a meaningful name (e.g. HT33A).

Results and Calculations The software records all sensor outputs and also calculates several derived

figures, and presents the recorded data in tabular form. The following columns are relevant to this exercise, and are suggested as suitable column headings if recording values manually:

Hot fluid volume flowrate

qvhot (m3/s) Multiply Fhot (litres/min) by 1.667x10-5

7-6


Hot fluid inlet temperature

T1 (C)

Hot fluid outlet temperature

T2 (C)

Cold fluid volume flowrate

qvcold (m3/s) Multiply Fcold (litres/min) by 1.667x10-5

Cold fluid inlet temperature

T3 (C)

Cold fluid outlet temperature

T4 (C)

You should also estimate and record the experimental errors for these measurements.

For each set of readings, the relevant derived results are calculated and presented with the following headings:

Reduction in hot fluid temperature Thot = T1 T2 (C)

Increase in cold fluid temperature Tcold = T4 T3 (C)

These values should be calculated manually if not using the software.

A graph may be plotted of the results. The software graph facility may be used for this.

Estimate the cumulative influence of the experimental errors on your calculated values for Thot and Tcold.

Compare the changes in temperature at the different flowrates. If time permits try different combinations of hot and cold fluid flowrate.

Conclusions You have demonstrated how, using a simple shell and tube heat exchanger, a

stream of cold fluid can be heated by indirect contact with another fluid stream at a higher temperature (the fluid streams being separated by a wall which conducts heat). This transfer of heat results in a cooling of the hot fluid.

Comment on the changes in Thot and Tcold when the flow of cold water is increased. The consequence of these changes will be investigated in a later exercise.

Note: To save time exercise HT33B can be carried out using the readings obtained from this exercise.

7-7


7.2 Practical Training Exercise HT33B

Objective To perform an energy balance across a Shell and Tube Heat Exchanger and

calculate the Overall Efficiency at different fluid flowrates.

Method By measuring the changes in temperature of the two separate fluid streams in

a shell and tube heat exchanger and calculating the heat energy transferred to/from each stream to determine the Overall Efficiency.

Equipment Required As exercise HT33A.

Equipment set-up If using the results from exercise HT33A then the equipment is not required.

If previous results are not available refer to the Set-up and Procedure sections of exercise HT33A.

Theory/Background Note: For this demonstration the heat exchanger is configured for

countercurrent flow (the two fluid streams flowing in opposite directions).

Mass flowrate (qm) = Volume flowrate (qv)

x Density of fluid () (kg/s)

Heat power (Q) = Mass flowrate (qm) x specific heat (Cp)

x change in temperature (T) (W)

Therefore:

Heat power emitted from hot fluid Qe = qmh. Cph (T1 - T2) (W)

Heat power absorbed by cold fluid Qa = qmc . Cpc (T4 - T3) (W)

7-8


Heat power lost (or gained) Qf = Qe - Qa (W)

Overall Efficiency =

QaQe

x 100 (%)

Theoretically Qe and Qa should be equal. In practice these differ due to heat losses or gains to/from the environment.

Note: In this exercise the cold fluid is circulated through the outer shell, if the average cold fluid temperature is above the ambient air temperature then heat will be lost to the surroundings resulting in 100%.

Procedure Use the results obtained from exercise HT33A.


figures, and presents the recorded data in tabular form. The following columns are relevant to this exercise, and are suggested as suitable column headings if recording values manually:




T1 (C)


T2 (C)



Cold fluid inlet temperature

T3 (C)

Cold fluid outlet temperature

T4 (C)

You should also estimate and record the experimental errors for these measurements.

For each set of readings, the software calculates the average hot fluid temperature (from T1 and T2) and the average cold fluid temperature (from T3 and T4) and then automatically provides values for the following variables. If recording data manually, calculate these values and obtain the variables from the tables on page 6-1:

7-9


Specific heat of hot fluid Cph kJ/kgK (From table 1)

Specific heat of cold fluid Cpc kJ/kgK (From table 1)

Density of hot fluid h kg/m3 (From table 2)

Density of cold fluid c kg/m3 (From table 2)


Mass flowrate (hot fluid) qmh (kg/s)

Mass flowrate (cold fluid) qmc (kg/s)

Heat power emitted Qe (W)

Heat power absorbed Qa (W)

Heat power lost Qf (W)

Overall Efficiency (%)


A graph may be plotted of the results. The software graph facility may be used for this.

Estimate the cumulative influence of the experimental errors on your calculated values for Qe, Qa, Qf and .

Compare the heat power emitted from/absorbed by the two fluid streams at the different flowrates.

Conclusions Explain any difference between Qe and Qa in your results.

Comment on the effects of the increase in the cold fluid flowrate.

Exercise HT33C should be carried out on completion of this exercise.

7-10


7.3 Practical Training Exercise HT33C

Objective To demonstrate the differences between cocurrent flow (flows in same

direction) and countercurrent flow (flows in the opposite direction) and the effect on heat transferred and temperature efficiencies.

Method By measuring the temperatures of the two fluid streams and using the

temperature changes and differences to calculate the heat energy transferred and the temperature efficiencies.





If using the HT30XC, or the HT30X with the optional software, run the HT33 software for the service unit used (HT30XC software must be used with the HT30XC and HT30X software with the HT30X, as the calibration for the sensors differs between the two service units). If using the HT30XC, select the Countercurrent exercise. If using the HT30X, select Exercise C and then select Countercurrent Operation on the software display option box.

Theory/Background Countercurrent operation

When the heat exchanger is connected for countercurrent operation the hot and cold fluid streams flow in opposite directions across the heat transfer surface (the two fluid streams enter the heat exchanger at opposite ends). The hot fluid passes through the seven tubes in parallel, the cold fluid passes across the tubes three times, directed by the baffles inside the shell.

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From the previous exercises:

Reduction in hot fluid temperature Thot = T1 - T2 (C)

Increase in cold fluid temperature Tcold = T4 - T3 (C)

Heat power emitted from hot fluid Qe = qmh. (Cp)h (T1 - T2) (W)

A useful measure of the heat exchanger performance is the temperature efficiency of each fluid stream. The temperature change in each fluid stream is compared with the maximum temperature difference between the two fluid streams giving a comparison with an exchanger of infinite size.

Temperature efficiency for hot fluid h = T1 T2T1 T3

.100 (%)

Temperature efficiency for cold fluid c = T4 T3T1 T3

.100 (%)

Mean Temperature Efficiency m =

h + c2

(%)

Cocurrent operation

When the heat exchanger is connected for cocurrent operation the hot and cold fluid streams flow in the same direction across the heat transfer surface (the two fluid streams enter the heat exchanger at the same end).

From the previous exercises:

Reduction in hot fluid temperature Thot = T2 T1 (C)

Increase in cold fluid temperature Tcold = T4 T3 (C)

Heat power emitted from hot fluid Qe = qmh. (Cp)h (T2 T1) (W)

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Temperature efficiency for hot fluid h = T3T2T1T2

.100 (%)

Temperature efficiency for cold fluid c = T3T2T3T4

.100 (%)

Mean Temperature Efficiency m =

h + c2

(%)

Procedure (Refer to the Operational Procedures on page 3-1 if you need details of the

instrumentation and how to operate it. The mains supply should be switched on before starting this experiment.)



If using HT30X, adjust the hot water control valve setting Vhot to give a hot water flow of 2 litres/min. If using HT30XC, click on the button for the hot water flow rate controller, set the controller to Automatic and enter a Set Point value of 2 litres/min. Apply and select OK.


When the temperatures are stable select the icon to record the following, or manually note the values: T1, T2, T3, T4, Fhot, Fcold

Close the cold water flow control valve.

If using the HT30XC, save the logged data by selecting Save or Save As from the File menu. Browse to the location you wish to place the saved data and give the results a meaningful name (e.g. HT33C Countercurrent Operation). If using HT30X software, create a new results sheet using the icon.

Change the system to cocurrent operation:

If using the HT30X, select the Cocurrent radio button on the software mimic diagram, and change the connections to the hot water inlet and outlet as follows:

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If using the HT30XC, select Load New Experiment... from the File menu, clicking on the Cocurrent Operation exercise radio button then select the Load button.

The connections to the heat exchanger are now configured for cocurrent operation where the hot and cold fluid streams flow in the same direction across the heat transfer surface (the two fluid streams enter the heat exchanger at the same end).

Adjust the cold water flow control valve to give a cold water flow rate reading of 1 litre/min (Hot and cold water flowrates the same as before).


If using the software, save the logged data by selecting Save or Save As from the File menu. Browse to the location you wish to place the saved data and give the results a meaningful name (e.g. HT33C Cocurrent Operation).


figures, and presents the recorded data in tabular form. The following columns are relevant to this exercise, and are suggested as suitable column headings if taking readings manually:



Hot fluid inlet T1 (C)

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temperature


T2 (C)


qvcold (m3/s) Multiply Fhot (litres/min) by 1.667x10-5

Cold fluid inlet temperature countercurrent flow

T3 (C)

Cold fluid outlet temperature countercurrent flow

T4 (C)

Note: In cocurrent flow T2 is the hot fluid outlet temperature and T1 is the hot fluid inlet temperature.

You should also estimate the experimental errors for these measurements.





Reduction in hot fluid temperature Thot (C)

Increase in cold fluid temperature Tcold (C)

Heat power emitted from hot fluid Qe (W)

Temperature efficiency for hot fluid h (%)

Temperature efficiency for cold fluid c (%)

Mean temperature efficiency m (%)


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Estimate the cumulative influence of the experimental errors on your calculated values for each of the above temperature differences and efficiencies.

Compare each set of calculated values.

Conclusions Your results from this exercise should indicate clearly the basic differences

between Cocurrent and Countercurrent flow through the shell and tube heat exchanger. The selection of the best arrangement for a particular application depends on many parameters such as Overall Heat Transfer Coefficient, Logarithmic Mean Temperature Difference, Fluid flowrate etc. These will be explained and investigated in later exercises.

Comment on the change in Thot and Tcold when the heat exchanger is converted from cocurrent to countercurrent operation.

Comment on the differences between the hot and cold fluid temperature efficiency for any given configuration and explain the changes in efficiency when the configuration is changed from cocurrent to countercurrent operation.

Note: To save time exercise HT33D can be carried out using the readings obtained from this exercise.

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7.4 Practical Training Exercise HT33D

Objective To determine the Overall Heat Transfer Coefficient for a Tubular Heat

Exchanger using the Logarithmic Mean Temperature Difference to perform the calculations (for cocurrent and countercurrent flow).

Method By measuring the temperatures of the two fluid streams and calculating the

LMTD from which the overall heat transfer coefficient can be calculated for each flow configuration.

Equipment Required As exercise HT33C.

Equipment set-up If using the results from exercise HT33C then the equipment is not required.

If previous results are not available refer to the Set-up and Procedure sections of exercise HT33C.

Theory/Background

Countercurrent operation Cocurrent operation

Heat power emitted from hot fluid Qe = qmh. (Cp)h (T1 - T2) (W)

Note: To eliminate the effect of heat losses/gains in the cold water stream the heat emitted from the hot fluid stream will be used in the calculations.

Because the temperature difference between the hot and cold fluid streams varies along the length of the heat exchanger it is necessary to derive an average temperature difference (driving force) from which heat transfer calculations can be performed. This average temperature difference is called the Logarithmic Mean Temperature Difference (LMTD) tlm.

LMTD tlm =

t 1 t 21n t 1 / t 2( )

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where t1 = (T2 T3) (C)

and t2 = (T1 T4) (C)

Note: This equation cannot produce a result for the case where t1 = t2.

LMTD tlm = ( ) ( )( ) (( ))T4T1/T3T21n

T4T1T3T2

(C)

In this example the equation for LMTD is the same for both countercurrent and cocurrent operation.

The heat transmission area in the exchanger must be calculated using the arithmetic mean diameter of the inner tubes.

Arithmetic mean diameter dm =

d o + d i2

(m)

Heat transmission length L = n.l (m)

where n = number of tubes = 7

l = heat transmission length of each tube = 0.144 (m)

L = 1.008

Heat transmission area = A = .dm.L (m2)

(dm can be used since r2/r1





T1 (C)


T2 (C)


qvcold (m3/s) Multiply Fhot (litres/min) by 1.667x10-5


T3 (C)


T4 (C)

Arithmetic mean diameter

dm (m)

Heat transmission area

A (m2)

You should estimate the experimental errors for these measurements.



Specific heat of hot fluid Cph kJ/kgK (From table 1 using T2 as the average temperature)

Density of hot fluid h kg/m3 (From table 2 using T2 as the average temperature)


Temperature difference t1 (C)

Temperature difference t2 (C)

Mass flowrate (hot fluid) qmh (kg/s)

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LMTD tlm (C)

Overall heat transfer coefficient U (W/m2K)


Estimate the cumulative influence of the experimental errors on your calculated values for tlm and U.

Conclusions You have now been introduced to the method for calculating the Overall Heat

Transfer Coefficient for a shell and tube heat exchanger. This is the most important characteristic of a heat exchanger. The effect of fluid flowrates and temperature differences between the hot and cold fluid streams will be investigated in later exercises.

Comment on the differences in t1 and t2 when the heat exchanger is configured for cocurrent and countercurrent flow. Comment on the resulting values for tlm and its effect on U.

Comment on any difference between the Overall Heat Transfer Coefficient for the same heat exchanger in cocurrent and countercurrent flow (with all other variables the same).

If you have conducted a similar exercise using a tubular heat exchanger (HT31 or HT36) or plate heat exchanger (HT32 or HT37) compare the performances and comment on the differences.

Exercise HT33E should be carried out on completion of this exercise.

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7.5 Practical Training Exercise HT33E

Objective To investigate the effect of changes in hot and cold fluid flowrate on the

Temperature Efficiencies and Overall Heat Transfer Coefficient.

Method By measuring the fluid temperatures at different combinations of hot and cold

fluid flowrate then calculating the corresponding Overall Heat Transfer Coefficient.

Equipment Required HT30XC Heat Exchanger Service Unit




If using the HT30XC, or the HT30X with the optional software, run the HT33 software for the service unit used (HT30XC software must be used with the HT30XC and HT30X software with the HT30X, as the calibration for the sensors differs between the two service units). If using the HT30XC, select the Countercurrent exercise. If using the HT30X, select Exercise E and then select Countercurrent Operation on the software display option box.

Theory/Background Refer to training exercises C & D for details of the relevant theory relating to

the calculation of the Temperature efficiencies and Overall Heat Transfer Coefficients.


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If using HT30X, adjust the hot water control valve setting Vhot to give a hot water flow of 1 litre/min. If using HT30XC, click on the button for the hot water flow rate controller, set the controller to Automatic and enter a Set Point value of 1 litre/min.



Repeat the above for different settings of the hot and cold fluid volume flowrate as follows:

Fhot (litres/min), Fcold (litres/min)

2 1

3 1

2 2

1 2

1 3

If using the HT30XC, save the logged data by selecting Save or Save As from the File menu. Browse to the location you wish to place the saved data and give the results a meaningful name (e.g. HT33E Countercurrent Operation). If using the HT30X software then create a new results sheet using the icon.

Change to cocurrent operation:

If using the HT30X, select the Cocurrent radio button on the software mimic diagram and change the connections to the hot water inlet and outlet as follows:

7-22


If using the HT30XC, select Load New Experiment... from the File menu and click on the Cocurrent Operation exercise radio button then select the Load button.


Adjust the cold water flow control valve to give a cold water flow rate of 1 litre/min.

If using HT30X, adjust the hot water control valve setting Vhot to give a hot water flow of 1 litre/min. If using HT30XC, click on the button for the hot water flow rate controller, set the controller to Automatic and enter a Set Point value of 1 litre/min.



Repeat the above for different settings of the hot and cold fluid volume flowrate as follows:

Fhot (litres/min), Fcold (litres/min)

2 1

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3 1

2 2

1 2

1 3

If using the HT30XC or HT30X software, save the logged data by selecting Save or Save As from the File menu. Browse to the location you wish to place the saved data and give the results a meaningful name (e.g. HT33E Cocurrent Operation).

Results and Calculations Technical data:

Inner tube inside diameter di = 0.00515 (m)

Inner tube outside diameter do = 0.00635 (m)

Heat transmission length L = 1.008 (total) (m)

The software records all sensor outputs and also calculates several derived figures, and presents the recorded data in tabular form. The following columns are relevant to this exercise, and are suggested as suitable column headings of recording data manually:




T1 (C)


T2 (C)




T3 (C)


T4 (C)


You should estimate the experimental errors for these measurements.

For each set of readings, the software calculates the average hot fluid temperature (from T1 and T2) and the average cold fluid temperature (from

7-24


T3 and T4) and then automatically provides values for the following variables. If recording data manually, calculate these values and obtain the variables from the tables on page 6-1:

Specific heat of hot fluid Cph kJ/kgK (From table 1 using T2 as the average temperature)

Density of hot fluid h kg/m3 (From table 2 using T2 as the average temperature)


Mass flowrate (hot fluid) Qmh (kg/s)


LMTD tlm (C)

Overall Heat Transfer Coefficient U (W/m2C)





Estimate the cumulative influence of the experimental errors on your calculated values for tlm, U and the temperature efficiencies.

Compare the results for U and the temperature efficiencies at the different hot and cold fluid flowrates.

Conclusions Your results from this exercise should indicate clearly the different effects of

hot and cold flowrate on the Overall Heat Transfer Coefficient and temperature efficiencies.

Comment on the effects of changing the hot and cold fluid flowrates.

If you have conducted a similar exercise using a tubular exchanger (HT31 or HT36) or plate heat exchanger (HT32 or HT37) compare the performances and comment on the differences.

Exercise HT33F should be carried out on completion of this exercise.

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7.6 Practical Training Exercise HT33F

Objective To investigate the effect of driving force with cocurrent and countercurrent

flow.

Method By measuring the fluid temperatures at different hot fluid inlet temperatures

then calculating the corresponding Temperature Efficiencies and Overall Heat Transfer Coefficients to determine the effect of the driving force.





If using the HT30XC, or the HT30X with the optional software, run the HT33 software for the service unit used (HT30XC software must be used with the HT30XC and HT30X software with the HT30X, as the calibration for the sensors differs between the two service units). If using the HT30XC, select the Countercurrent exercise. If using the HT30X, select Exercise F and then select Countercurrent Operation on the software display option box.

Theory/Background Refer to training exercises C & D for details of the relevant theory relating to

the calculation of the Temperature efficiencies and Overall Heat Transfer Coefficients.


7-26




If using HT30X, adjust the hot water control valve setting Vhot to give a hot water flow of 2 litres/min. If using HT30XC, click on the button for the hot water flow rate controller, set the controller to Automatic and enter a Set Point value of 2 litres/min.



Repeat the above for different settings of the hot water temperature controller as follows: 50C, 60C & 70C

If using the HT30XC, save the logged data by selecting Save or Save As from the File menu. Browse to the location you wish to place the saved data and give the results a meaningful name (e.g. HT33F Countercurrent Operation).

Change the system to cocurrent operation:

If using the HT30X, create a new results sheet in the software using the icon, select the Cocurrent radio button on the software mimic diagram, and change the connections to the hot water inlet and outlet as follows:

7-27


If using the HT30XC, select Load New Experiment... from the File menu and click on the Cocurrent Operation exercise radio button then select the Load button.


Adjust the cold water flow control valve to give a flow rate reading of 1 litre/min.

If using HT30X, adjust the hot water control valve setting Vhot to give a hot water flow of 2 litres/min. If using HT30XC, click on the button for the hot water flow rate controller, set the controller to Automatic and enter a Set Point value of 2 litres/min.

Set the temperature controller to 40C.


When the temperatures are stable, select the icon to record the following or record the values manually: T1, T2, T3, T4, Fhot, Fcold

Repeat the above for different settings of the hot water temperature controller as follows: 50C, 60C & 70C

If a supply of cold water is available at variable temperature the exercise can be repeated for different cold water inlet temperatures. Remember to create a new results sheet for each set of results, and to configure the hardware and/or software for countercurrent or cocurrent operation as required. The software will not correctly calculate the derived values if it has not been properly configured.

If using the HT30X or HT30XC software, save the logged data by selecting Save or Save As from the File menu. Browse to the location you wish to place the saved data and give the results a meaningful name (e.g. HT33F Cocurrent Operation).

Results and Calculations Technical data:

Inner tube inside diameter di = 0.00515 (m)

Inner tube outside diameter do = 0.00635 (m)

Heat transmission length L = 1.008 (total) (m)

7-28


The software records all sensor outputs and also calculates several derived figures, and presents the recorded data in tabular form. The following columns are relevant to this exercise, and are suggested as suitable column headings if recording data manually:

Hot fluid volume flowrate qvhot (m3/s) Multiply Fhot (litres/min) by 1.667x10-5

Hot fluid inlet temperature T1 (C)


T2 (C)

Cold fluid volume flowrate qvcold (m3/s) Multiply Fcold (litres/min) by 1.667x10-5


T3 (C)


T4 (C)

You should also estimate the experimental errors for these measurements.






Mass flowrate (hot fluid) Qmh (kg/s)


LMTD tlm (C)

Overall Heat Transfer Coefficient U (W/m2C)


7-29





Estimate the cumulative influence of the experimental errors on your calculated values for Tlm, U and the temperature efficiencies.

Compare your derived results at the various differential fluid temperatures.

Conclusions Your results from this exercise should indicate clearly the effect of driving

force (temperature difference between the hot and cold fluid streams) on the Overall Heat Transfer Coefficient and Temperature Efficiencies.

If you have conducted a similar exercise using a tubular heat exchanger (HT31 or HT36) or plate heat exchanger (HT32 or HT37) compare the performances and comment on the differences.

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7.7 Exercise HT33G: Project Work

To investigate heat loss from the Shell and Tube Heat Exchanger Practical training exercises HT33A to HT33F are performed with hot water flowing through the inner tubes and cold water flowing through the outer annulus. This arrangement minimises the loss of heat from the heat exchanger because the temperature difference between the cold water stream and the ambient air is relatively small. (If the ambient air temperature is higher than the average temperature of the cold water stream then a small gain in heat can occur.)

An investigation of heat loss from the heat exchanger when the hot water flows thorough the outer annulus would provide a suitable project for students who have completed the previous training exercises. The quick release fittings between the heat exchanger and the service unit will allow the hot and cold fluid streams to be interchanged.

By comparing the heat power emitted from the hot water with the heat power absorbed by the cold water, the heat loss form the exchanger to the surroundings can be determined. Details of the necessary measurements and calculations are given in practical training exercise B.

Note: As the outer annulus of the heat exchanger is manufactured using clear acrylic tube, the hot water flowing through the outer annulus should be limited to 65C to minimise softening of the tube. Similarly, the heat exchanger should not be operated with hot water in the outer annulus for long periods of time.

To investigate reduction in heat transfer coefficient due to fouling of the heat transfer surfaces

The effect of fouling of the heat transfer surfaced can provide an interesting project for students who have completed the previous training exercises.

The construction of the heat exchanger using O ring seals allows the inner tubes to be easily removed and replaced with alternative tubes inside which the surface has been pre-fouled.

Seven metal tubes 6.35mm () outside diameter, 0.6mm wall thickness and 166mm long (not supplied) should be provided for the student to foul by coating the inside diameter with a suitable insulating layer.

Note: The action of pushing the metal tube through an O ring prevents the application of fouling to the outer surface of the metal tube.

7-31


If alternative tubing is not available then the existing tubes can be fouled but it will be necessary to remove the fouling before using the heat exchanger for normal measurements.

To remove the inner metal tubes from the heat exchanger, disconnect the quick release fittings from the exchanger, then carefully remove the headers (end plates) from the exchanger assembly (sealed using O ring seals) before pushing out the individual metal tubes. If the tubes do not move easily a small amount of wetting agent should be poured into the O ring housings at the end of each tube to prevent damage to the O ring seals.

Before re-inserting the metal tubes, or installing alternative tubes with fouling on the inner surface, lubricate the O ring seals with a small amount of wetting agent.

Designing an alternative heat exchanger An interesting project for students who have completed the previous training exercises is to build and test a heat exchanger of their own design. Provided that the alternative heat exchanger is constructed with inlet and outlet connections to suit the quick release fittings on the HT33 Shell and Tube Heat Exchanger, then the fittings used on the HT33 may be transferred directly, complete with the temperature sensors fitted. The alternative heat exchanger can then be connected directly to the HT30X/HT30XC service unit for evaluation.

The inlet and outlet tubes should be 9.5mm (3/8) outside diameter to allow direct connection to the fitting supplied with the HT33 Shell and Tube Heat Exchanger. If using the temperature sensors only from the HT33 then the tappings for the temperature sensors should be 9.5mm (3/8) inside diameter.

Practical training exercises HT33A to HT33F may be applied to the students own design of heat exchanger as appropriate.

Typical projects might include:

A Shell and Tube Heat Exchanger constructed with different internal dimensions, e.g. different tube diameter/shell diameter.

A Shell and Tube Heat Exchanger constructed using different materials, e.g. tube bundle manufactured from copper.

A Shell and Tube Heat Exchanger with different tube bundle geometry (spacing of tubes or different pattern/number of tubes).

A Shell and Tube Heat Exchanger with the tubes arranged for multi-pass operation (ends of tube bundle connected to allow hot fluid to flow through the tubes in series instead of parallel).

7-32

8 Appendix A: Installation Guide

The HT33 Shell and Tube Heat Exchanger must be used in conjunction with the HT30X or HT30XC Heat Exchanger Service Unit.

Before mounting the HT33 Shell and Tube Heat Exchanger on a HT30X/HT30XC Heat Exchanger Service Unit ensure that the service unit has been assembled and connected to the appropriate services as described in the instruction manual supplied with the service unit.

1 Check that the HT30X/HT30XC service unit and the Armfield HT30 range software has been installed as described in the HT30X/HT30XC product manual (provided with the service unit). If used, the PC on which the software has been installed should be located close to the service unit (a compatible PC is required if using the HT30XC).

2 Remove the HT33 accessory from any packaging and position the accessory on the HT30X/HT30XC plinth so that the holes in the HT33 baseplate are located over the studs on the plinth top.

3 Secure the HT33 to the plinth using the thumb nuts provided.

4 Connect the flexible tubing on the HT33 to the quick-release fittings on the service unit as shown:

If using the HT30X:

8-1

If using the HT30XC:

5 Direct the tubing carrying the cold water out of the exchanger into a suitable drain.

6 Check that the HT30X/HT30XC service unit is connected to suitable mains water and mains electricity supplies (as described in the manual supplied with the service unit), and that the water and electricity supplies are switched on.

7 If using the HT30XC, check that the service unit is connected to the PC using the USB cable provided, and that the PC is switched on. Check that the red and green USB indicator lights on the front panel of the HT30XC are illuminated.

If using the HT30X with optional interface device and software, check that the interface device is connected to the service unit and to the PC. Check that the PC is switched on, and that the red and green indicator lights on the interface device are illuminated.

8 Switch on the service unit (using the mains switch on the front of the unit). If using the HT30XC, check that the Emergency Stop button is released (pulled out).

9 If using the HT30X with software, or the HT30XC, run the HT33 software and select Exercise A (HT30X) or the Countercurrent Exercise (HT30XC). Check that the software reads IFD OK in the bottom right-hand corner of the screen.

10 If using a PC, select the mimic diagram in the software by clicking on the icon.

11 If using the HT30XC, select the Power On switch on the software mimic diagram.

8-2

12 If using the HT30X, switch on the hot water circulating pump then fully open the hot water flow control valve. Run the pump until all air bubbles have been expelled from the hot water circuit. Top up the priming vessel with clean (preferably de-ionised or de-mineralised) water if the level drops more than a centimetre or so below the top. Switch off the pump.

If using the HT30XC, select the Hot Water Pump Control button. In the controller window, set the controller to Manual and then set the Hot Water Pump Speed to 100% using the Manual Control box in the right-hand pane of the window. The hot water pump should begin to operate. Run the pump until the hot water circuit of the heat exchanger has filled with water and all bubbles have been expelled from the circuit. Top up the hot water tank with clean (preferably de-ionised or de-mineralised) water if the level drops below the tip of the level sensor. Set the Hot Water Pump Speed back to 0%. The pump should cease operation. Close the controller window.

13 Set the Cold Water Valve to fully open (100%), either manually (if using the HT30X) or using the software (if using the HT30XC). The valve should operate and cold water begin to flow through the cold water circuit. Allow water to flow until any bubbles have been eliminated, then close the valve again (set the valve back to 0%).

The HT33 accessory is now installed and primed ready for use.

Refer to the HT30X/HT30XC manual for further information on the service unit and its operation.

Refer to the Operational Procedures and Laboratory Teaching Exercises in this manual for more information on the operation of the HT33 and the investigations that can be performed using this Heat Exchanger. The Teaching Exercises are also

available from within the HT33 software Help Text.

8-3

shell and tube

Documents

use of water

ht30xc service unit

temperature of water

tube heat exchanger

instruction manual ht33

circulator unit

safety instructions

electrical safety