em306 lab manual jan 2014

FACULTY OF ENGINEERING, TECHNOLOGY & BUILT

ENVIRONMENT

SUBJECT CODE & NAME:

EM306 THERMODYNAMICS II

Lecturer Name: Dr. LAI Nai Yeen Gavin

Tutor Name: Ms. Nor Fazilah

Student Name :

Student ID :

Semester / Year : January – April 2014

EM306| Thermodynamics II

Updated Dec 2013 1 | P a g e

TABLE OF CONTENTS

SN Content Page

1 Experiment #1 Air Conditioning Unit 2

2 Experiment #2 General Observation of Cooling Tower and Relationship

between Cooling Load and Cooling Range

3

3 Experiment #3 End State Properties of Air and Steady Flow

Equations

5

4 Experiment #4 Refrigeration System 6



Experiment 1 – Title: Air Conditioning Unit

Objective

To study the cooling effects and to determine the cooling power of the cooling coil

To study the dehumidification effects and to determine the cooling power of the cooling coil

To study the heating effects and to determine the heating power of the heaters

Introduction / Instruction / Procedure / Guideline

Design and conduct experiments to achieve the above objectives. Students should run the radial fan at

selected air speed and choose the selected processes. Additionally, students should also record the air

temperature and relative humidity at the inlet and outlet of the coil and the differential pressure

reading across the orifice when a steady state is reached.

**Note: Process will stabilize in approximately 15 minutes.

Results and Discussion

1. For each process, plot these two state points (inlet & outlet points) on the Psychrometric chart.

2. Analyze the Specific Volume of Outlet Air, v (m3/kg dry air) and Absolute Humidity of Outlet

Air, (kg/kg dry air) from Psychrometric chart.

3. Assess the cooling power of the cooling coil and heating power of the heaters. (Please show your

calculation)

4. Complete the name of unit assembly of Air-Cond unit (AC01) – Refer attachment.



Experiment 2 – Title: General Observation of Cooling Tower and Relationship between Cooling

Load and Cooling Range

Objective

To observe the processes within a forced draught cooling tower

To investigate the relationship between cooling load and cooling range


Observation of Forced Draught Cooling Tower

1. Perform the general start-up procedures and observe the forced draught cooling tower proves.

2. As the warm water enters the top of the tower, it is fed into channels from which it flows via

water distribution system onto the packing. The channels are designed to distribute the water

uniformly over the packing with minimum splashing.

3. The packing surfaces are easily wetted and the water spreads over the surfaces to expose a large

area to the air stream.

4. The cooled water falls from the lowest packing into the basin and then is pumped to the simulated

load in the load tank.

5. During the process, some water is lost due to the evaporation. Thus, "make-up" water must be

supplied to keep the amount of water in the cooling system constant. The make-up is observed

flowing past the float-controlled valve in the load tank.

6. A “droplet arrester”, or “mist eliminator” is fitted at the tower outlet to minimize loss of water due

to escape of droplets of water (resulting from splashing, etc.) which is entrained in the air stream.

This loss does not contribute to the cooling, but must be made good by "make-up". The droplet

arrester causes droplets to coalesce, forming drops that are too large to be entrained and these falls

back into the packing.

7. The fan drives the air upward through the wet packing. At air outlet, the air leaving the cooling

tower is almost saturated, i.e. Relative Humidity is ~100%. The Relative Humidity at the air outlet

is much higher than the Relative Humidity at the air inlet. The increase in the moisture content of

the air is due to the evaporation of water into steam and the "latent heat" for this account for most

of the cooling effect.

8. When the cooling load is switched off and the unit is allowed to stabilize, it is found that the water

leaves the basin at temperature close to the wet bulb temperature of the air entering. Wet bulb

temperature is lower than the dry bulb temperature and this varies according to the local

atmospheric conditions (i.e. pressure and relative humidity).

9. With no load, the water would be cooled to the incoming wet bulb temperature. However, the

condition cannot be achieved since the work done by the pump transfers about 40W to the water.



Relationship between Cooling Load and Cooling Range

1. Set the system under the following conditions and allow stabilizing for about 15 minutes.

i. Water flow rate : 2.0 LPM

ii. Air Flow : Maximum

iii. Cooling load : 0.0 kW

2. After the system stabilized, record a few sets of the measurements such as temperatures, orifice

differential pressure, water flowrate and heater power, then obtain the mean value for calculation

and analysis.

3. Without changes in the conditions, increase the cooling load to 0.5 kW. When the system

stabilized, record all data.

4. Similarly, repeat the experiment at 1.0kW and 1.5kW.

5. The tests may be repeated:

i. At other water flow rates ii. At other air flow rate


1. Outline your observation of the process within a forced draught cooling tower in the lab.

2. In UCSI University North Wing Campus, cooling towers are used in the air conditioning system.

Explain the principle of this system and use some sketches as illustrations to show the cycle of

cooling the classrooms in the campus.

3. Plot a graph of cooling load vs. cooling range. Analyze the relationship.



Experiment 3 – Title: End State Properties of Air and Steady Flow Equations

Objective

To determine the “end state” properties of air and water from tables or charts

To determine energy and mass balances using the steady flow equation.


Based on experience conducting previous experiment of cooling tower, design and conduct an

experiment of a modern evaporating system. The experiment should determine the “end state”

properties of air and . Student also needs to show the calculations to draw up energy and mass

balances.

The cooling tower unit should be prepared, start and allow stabilizing under following suggested

conditions:

Water flow rate = 2.0 LPM

Air flow = Maximum

Cooling load = 1.0kW

After the conditions have stabilized, observe and examine the processes of the water system

and air system of the cooling tower.


1. Determine the “end state” properties of air and water from tables or charts.

2. Calculate the energy and mass balances by using the steady flow equation.

3. Evaluate and discuss the major factor and issues affecting the accuracy of the measurements and

cooling tower performance.



Experiment 4 – Title: Refrigeration System

Objective

To investigate the effect of condensing and evaporating temperatures on the refrigeration rate and

condenser heat output.

To determine the compression ratio and its effect on system performance


1. Ensure that the unit is air free by venting the air from the condenser.

2. Adjust the condenser cooling water flow, to the maximum and Evaporator cooling water flow, to

1.5LPM. The pressure at which the condenser stabilizes will depend upon the water inlet

temperature.

3. Allow the temperature and pressure readings to stabilize. Then, record all the system parameters.

4. Reduce the condenser cooling water flow rate to increase the condenser pressure by

approximately 0.1 kgf/cm2.

5. Allow the unit to stabilize and again record all of the system parameters.

6. Repeat for increasing condenser pressures to the minimum readable value on the condenser water

flow meter is reached.


1. Compare the Heat Transfer Rate in Condenser Vs Condensing Temperature (with the help of a

graph)

2. Assess the Evaporator Heat Transfer, Q E(W) and Condenser Heat Transfer, Q C(W)

3. Compare the Heat Transfer Rate in Condenser Vs Compressor Pressure Ratio (with the help of a

graph)

4. Assess the Evaporator Heat Transfer, Q E(W) and Condenser Heat Transfer, Q C(W).

5. Determine the pressure ratio for every condenser pressure readings obtained (Pc/PE).



Attachment:

General Introduction (Air Conditioning Unit AC01)

Air-conditioning is a widespread feature of building engineering, designed to make the

occupants feel comfortable and at ease. The main functions of an air-conditioning system include

heating and cooling, and humidifying and dehumidifying in order to create the desired indoor air conditions.

The SOLTEQ®

Air-Conditioning Unit (Model: AC 01) includes all the components found in air-

conditioners installed in buildings. It additionally has a complete refrigeration unit, enabling the

system to cover most of the spectrum of experiments in the field of refrigeration and air-conditioning engineering.

T

T T T T

DP

AT 1

RH 1

AT 2

RH 2

AT 3

RH 3

AT 4

RH 4

AT 5

RH 5

STEAM

HUMIDIFIER

RADIAL FAN

PRE-HEATER EVAPORATOR RE-HEATER ORIFICE

COMBINED TEMPERATURE /

HUMIDITY TRANSMITTER

DIFFERENT

PRESSURE

MANOMETER

Figure 1: Process Schematic Diagram for AC System

Air Duct Cross Sectional Area, A = 0.09 m2

Specific Heat Capacity of Air, Cp = 1.006 kJ/kg.K

Orifice Differential Pressure, DPDP 102.0' (mmH2O)

Air Mass Flowrate,

1

'0592.0

v

DPma

Cooling Power Power,

Heating Power (kW),

Heat Transfer Efficiency (%)

%100P

QEfficiency



Unit Assembly of Air Conditioning Unit - AC01

Figure 2: Unit Construction for Air Conditioning Unit

1. _______________________ 9. ________________________

2. _______________________ 10. ________________________

3. _______________________ 11. ________________________

4. _______________________ 12. ________________________

5. _______________________ 13. ________________________

6. _______________________ 14. ________________________

7. _______________________ 15. ________________________

8. _______________________

* Please submit this together with your report

1

5

7

6

14

15

13

9

10

2

8

4

3

11

12



General Introduction ( Bench top cooling Tower HE152)

The SOLTEQ

® Basic Cooling Tower Unit (Model: HE152) has been designed to demonstrate

the construction, design and operational characteristics of a modern cooling system. The unit

resembles a full size forced draught cooling tower and it is actually an "open system" through

which two streams of fluid (in this case air and water) pass and in which there is a mass transfer from one stream to the other. The unit is self-contained supplied with a heating load and a

circulating pump. Once energy and mass balances are done, students will then be able to

determine the effects on the performance of the cooling tower by the following parameters:

a) Temperature and flow rate of water

b) Relative Humidity and flow rate of air c) Cooling load

Additionally, a Packing Characteristics Column (optional) is available for SOLTEQ® Basic

Cooling Tower Unit (Model: HE152). This column is designed to facilitate study of water and air conditions at three additional stations (I, II and III) within the column. This enables driving

force diagrams to be constructed and the determination of the Characteristic Equation for the

Tower.

1. Orifice Calibration Formula:

Mass flow rate of air and vapor mixture,

bav

xm

10137.0

The mass flow rate of dry air,

10137.0

ba

av

xm

Where,

x = orifice differential in mmH20,

Bav = specific volume of air at the outlet

= humidity ratio of the mixture

2. Pump Work Input = 80W (0.08kW)

3. Column Inner Dimension = 150 mm x 150 mm x 600 mm

4. Packed column: 110 m2/m

3

5. Inner diameter of Make up tank = 74mm



GENERAL OPERATING PROCEDURES (Refrigeration Cycle Demonstration Unit RF166)

The SOLTEQ® Refrigeration Cycle Demonstration Unit (Model: RF166) has been designed to study

the thermodynamics of the vapor compression cycle. The unit is constructed as a bench top unit. The

unit operates as a refrigerator so that experiments on the evaluation of refrigeration cycle and thermodynamic energy balances of the condenser, evaporator, and compressor can be performed. The

evaporation and condensation can be observed through the glass tubes.

A refrigerator is defined as a machine whose prime function is to remove heat from a low temperature

region. Since energy cannot be destroyed, the heat taken in at a low temperature must be dissipated to

the surroundings.

Refrigerators are cyclic devices, and the working fluids used in the refrigeration cycles are called

refrigerants. A refrigerator requires an external energy for it to operate. This energy input may be in

the form of work, or a heat transfer at a high temperature. The most common type of refrigerator uses a work input and operates on the vapour compression cycle.

Condenser Pressure PT 1 ( Abs Bar)

Evaporator Pressure PT 2 ( Abs Bar)

Condenser Water Flowrate FT 1 (LPM)

Evaporator Water Flowrate FT 2 (LPM)

Condenser Temperature T 1 (oC)

Condenser Water Inlet Temp. T 2 (oC)

Condenser water Outlet Temp. T 3 (oC)

Evaporator Temperature T 4 (oC)

Evaporator Water Inlet Temp. T 5 (oC)

Evaporator Water Outlet Temp. T 6 (oC)

Table 6.1: System Parameter

em306 lab manual jan 2014

Documents

cooling load

cooling power

cooling coil

cooling effects

cooling range objective

forced draught cooling

cooling system constant

air temperature