Run around coil system for efficient heat recovery

The TROX run around coil system

Hygienic, safe, efficientRun around coil systems (RAC) are regenerative heat recovery systems in which the airflows are completely separated from one another. As a result, they are suitable for applications in which no leakages between the supply and extract air are desired or permitted for hygienic reasons: for example in hospitals as well as in the food and pharmaceutical industries. They are also used if supply and extract air units are set up separately from one another due to the layout situation.

A run around coil system consists of at least one heat exchanger in the supply and extract airflow which are connected to one another by a hydraulic circuit. The heat transfer fluid is usually a mix of glycol and water.

Investment with a future – up to 80% heat recoveryThe Ecodesign Directive prescribes that from 2018 onwards, air handling units must offer a heat recovery efficiency of more than 73%, and RAC systems more than 68%. A run around coil system from TROX with a TROX hydraulic unit including special RAC control guarantees highly efficient heat recovery. Heat recovery efficiencies of up to 80% can be achieved with this system.

To achieve this energy efficiency, several heat exchangers with a special internal counterflow system in the airflow are connected in series. The hydraulic circuit is connected in the opposite direction to the airflow so as to generate a consistent temperature profile between the air and the exchanger operating fluid.

System expertise from TROXTROX has optimally adapted the hydraulic unit to the TROX X-CUBE using tried-and-tested system expertise. The entire system offers convincing efficiency and extensive functions.

ODA

ETA

SUP

2

The advantages at a glance

Reliable data by certified design softwareThe X-CUBE Configurator sales tool has been certified by the Association of Air Handling Unit Manufacturers for configuration of RAC systems as well. The calculation software has been specially developed in-house at TROX. Planners and system owners will receive precise and reliable figures for their planning within a very short time.

Intelligent control engineeringThe innovative control engineering from TROX networks all components and units into one intelligent overall system for maximum safety and energy efficiency.

Made in GermanyUsing the latest production technology in the plant built specially for the X-CUBE in Anholt, TROX guarantees the best quality and short delivery lead times. Needless to say TROX implements the relevant industry standards and has all its components and processes certified.

High degree of flexibilityThe TROX hydraulic unit is available with three casing variants: ■ Open frame■ Closed casing■ Weatherproof construction variant

Easy installationThe X-CUBE and the hydraulic unit are delivered pre-assembled and ready to operate.

Intuitive operationHydraulic units can be easily and conveniently controlled and checked using operating terminals on the units as well as via a web browser. Virtually all status information is available at a glance.

Seamless integration with modern building management systemsHydraulic units can be integrated into modern instrumentation and control systems by means of Modbus TCP/IP and BacNet IP, or conventional analogue signals.

High energy efficiencyThe TROX X-CUBE and TROX hydraulic unit have been consistently designed for energy efficiency. Low life-cycle costs are made possible by the design principle, insulation, leak-tightness, heat recovery, energy-efficient actuators and the intelligent control engineering.

3

■

The perfect overall system

GLT OFF

Modus:Benutzer:Logo Countdown:06-12-2016 14:16:44

Kreislaufverbundsystem

Zuluft

Abluft

197 kW

- 6,5 °C

- 6,5 °C

7,5 m3/h22.500 m3/h

100 %

100 %0 %

18 °C

18 °C

197 kW

AutomatikTROX839 s

GLT OFF06-12-2016

Kreislaufverbundsystem

Abluft

197 kW

- 6,5 °C

7,5 m

Modus:Benutzer:Logo Countdown:06-12-2016 14:16:44

Kreislaufverbundsystem

Zuluft

Abluft

197 kW

- 6,5 °C

7,5 m3/h22.500 m3/h

100 %

100 %0 %

18 °C

18 °C

197 kW

AutomatikTROX839 s

Optimum flow rate relationshipThe TROX hydraulic unit continuously balances

the exchanger operating fluid flow rate with the

air flow rate, and adapts them optimally.

This guarantees high energy efficiency in all

operating statuses.

Extract air unit

State-of-the-art technology ■ High-pressure multistage centrifugal pumps

with IE4 motors■ High-quality stainless steel press-fit system

up to nominal width 65 mm■ From nominal width 65 mm onwards,by

coupling system with removable connections■ Optional thermal insulation of the pipelines

Plausibility checks for greater efficiency The TROX hydraulic unit monitors all internal

temperatures to detect all non-economical

operating parameters and report them.

High operational reliabilityPressure monitors with two switching points, a

membrane expansion vessel and an 8 bar safety

valve in the TROX hydraulic unit ensure high

operational reliability.

4

■

Supply air unit

Optional cold and heat feed A RAC system creates a closed hydraulic circuit, which means it is possible to feed additional heating or cooling capacity into the system. This option makes the air handling unit more compact, and eliminates the air-side pressure loss from cooling coils or heating coils. Depending on the building‘s requirement, the feed capacity can be controlled by various hydraulic circuits.

Flexible feed control

■ Throttle circuitE.g. for systems with condensing boilers or district heating connection

■ Diverting circuitFor a variable flow rate in the consumer circuit and a constant flow rate and pressure in the source circuit – not suitable for district heating connections

■ Mixing circuitE.g. for constant flow through the consumer circuit and variable flow through the source circuit

■ Injection circuit– Optimum control response– Temperature control via availability of mixed

flow through the consumer circuit at all times– Not suitable for district heating connections

M

ϑ

Throttle circuit

Mϑ

Diverting circuit

M

ϑ

Mixing circuit

ϑ M

Injection circuit

ConsumerSource

ConsumerSource

ConsumerSource

ConsumerSource

5

Suitable for all requirements

Dehumidification recoveryBy using dehumidification recovery (referred to as: DHR), it is possible to reduce mechanical cooling for dehumidification of the outside air, e.g. for laboratories, clean rooms and the like. At the same time, this arrangement means there is no need for subsequent heating using conventional heating technology. A cooling coil (PCW) in the supply air unit dehumidifies the warm, moist outside air. The downstream heat exchanger integrated in the RAC system provides subsequent heating of the dehumidified air to bring it to nominal temperature. The heat recovered from the extract air is used for this.

The operating fluid cooled by an integral heat exchanger in the hydraulic circuit is supplied to a further heat exchanger located upstream of the dehumidifying cooling coil in the airflow direction. This heat exchanger provides pre-cooling of the warm outside air, thereby reducing the mechanical cooling capacity that has to be supplied from outside the system.

Indirect adiabatic coolingAn adiabatic humidifier can be installed in the extract airflow to save the need for mechanical cooling capacity in summer. It cools the extract air by adiabatic humidification. The modification takes place until the air is approaching saturation point. The cooled air absorbs the heat from the glycol mixture in the RAC, thereby cooling it down. In turn, the cooled operating fluid is used for pre-cooling of the warm outside air.

Preheating/filterIf the outside air is moist, for example on foggy days, water can collect in the outside air filter and represent an optimum growth medium for bacteria and mould. Filter preheating can be installed in the RAC to prevent this happening. An additional heat exchanger before the first filter stage heats the outside air by 3 - 5 K which prevents moisture penetration by reducing the relative outside humidity. The heat exchanger is built to enable it to be cleaned effectively.

Twin pumpTwo pumps can be installed in parallel to increase the operational reliability or efficiency in part-load mode. 100% redundancy is also possible, as is continuous parallel operation.

Temperature controlIf necessary, the RAC unit can take over the entire temperature control function in the air handling unit. Corresponding sensors are arranged in the air handling unit for this purpose.

Volume flow rate measurementActive pressure registration of the fan enables the volume flow rate of the air handling unit to be calculated.

Δp

M

AB

AB

1.5

2.5

A

B

M

.

.

ϑ

φ

ϑ

φ

Δp

AUL ZUL

ϑ ϑ

φ φ

Software zur Darstellung von Prozessen imMollier - h, x – Diagramm ©

04.05.2017 16:47

-15

-10

-5

0

5

10

15

20

25

30

35

40

45

50

55

60

65

70

75

80

85

90

95

100

0 2 4 6 8 10 12 14 16 18 20 22 24 26 28 30 32 34 36 38 40 42 44 46 48 50

rein

Abluft rein

Luftdruck [Pa] 1013,25 hPa

"Normal"-Dichte =1,2 kg/m³

Wassergehalt [g/kg]

Tem

pera

tur [�C

]

spe

zifis

che

Enth

alpi

e [k

J/kg

]

100%90%

60%

50%

40%

30%

10%

70%

rela

tive

Luftf

euch

tigke

it [%

]

Nutzereingaben:

20%

80%

ILK-hx-Dia [Software zur Darstellung von Prozessen im Mollier - h, x – Diagramm] © Download unter http://www.ilkdresden.de/hxdia

ILK Dresden Institut für Luft- und Kältetechnik Dresden

DHR

PCW

HRS

6

Δp

000[m³/h]

000

A

B

AB

AB

Δp

AB

AB

A

B

M

50%50%

100% 100%

ϑ

φ

ϑ

φ

ϑ ϑ

ϑ

ϑ ϑ

ϑ

ϑ

ϑ ϑ

ϑ ϑ

φ

φ

Diagram with dehumidification recovery

Preheating/filter

DHRC1.1

2.1

6.3

1.5

6.4 3.1

1.2

2.2

M X.5.1

6.1

6.2

4.84.9

4.1

4.2

4.7

4.10

4.6

4.54.4

4.3

X.5.2

1.X.X

X.5.2

X.5.3

X.5.2

4.104.11

4.114.10

7.1

3.23.2

2.3

1.3

1.4

2.4

X.5.1

X.5.3X.5.1

X.5.2

1.5

M

M

M

Dehumidification recoveryDHRC

Air volume measurementSUPOutput control

Heating coil

Icing protection

Volume flow sensor

[bar]

Feed heating capacity

Pressure monitoring

Output control heat recovery

Upon

requ

est

AdiabaticEXA humidification

Adiabatic EXA humidification

Temperature control/DHRC

Air volume measurementETA

Twin pump100% redundancy

Twin pump50% redundancy

Injection circuit

Mixing circuitThrottle circuit

Diverting circuit

ODA

EHA ETA

SUP

Upon request

Upon request

8

Δp

000

000

A

B

AB

AB

Δp

):

OX o. ext. Beistellung

Option

TROX wenn Option gewählt

50%50%

100%100%

ϑ ϑ

ϑ ϑ

ϑ

ϑ ϑ

ϑ ϑ

φ φ

φ φ

ϑ ϑ

ϑ ϑ

Diagram with heating and cooling feed

Preheating/filter

4.1

4.2

4.4

4.7

4.10

4.6

4.5

4.3

4.9

4.8

2.X.X

1.X.X

4.10

4.10

7.1

4.11

4.11

X.5.2 X.5.1 X.5.2

X.5.3

X.5.1

X.5.2X.5.2

X.5.1 X.5.3 X.5.1

Temperature control Temperature control

Upon request Upon request

M M

MM

Air volume measurementSUP

Icing protection

Volume flow sensor

[m3/h]

M

[bar]

Feed heating capacity

Feed cooling capacity

Pressure monitoring

Output control heat recovery

Adiabatic EXA humidification

Adiabatic EXA humidification

Temperature control/DHRC

Twin pump 100 % redundancy

Twin pump 50 % redundancy

Injection circuit

Mixing circuitThrottle circuit

Diverting circuit

EHA ETA

ODA SUP

1.1

2.1

3.1

1.2

2.2

1.31.4

2.4

3.2

2.3Upon request

Upon request

Air volume measurementETA

9

Novatic Color Company, Dresden, Germany

Henninger Turm, Frankfurt, Germany

Hospital, Augsburg, Germany

University Hospital, Heidelberg, Germany

Inselhalle (Reception hall), Lindau, Germany

Photo credits: © Uniklinikum Heidelberg, Henninger Turm Frankfurt Wikimedia CC 3.0 Echtner, Klinikum Augsburg Wikimedia CC 3.0, Richard Reinhardt

Inselhalle Lindau © Auer Weber Architects, Munich, Lackierfabrik Novatic Dresden, Wikimedia CC 3.0 Novatic Dresden

X-CUBE Run around coil systems in operation

7

TROX GmbHHeinrich-Trox-Platz47504 Neukirchen-VluynPhone +49(0)2845 2020Fax +49(0)2845 202265www.troxtechnik.comtrox@trox.de SF

/201

7/5/

KVS/

DE/e

n •

Subj

ect

to c

hang

e •

All r

ight

s re

serv

ed ©

TRO

X Gm

bH (

05/2

017)