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Products  |  Thermal Engineering and HVAC  |  Refrigeration and Air Conditioning Technology  |  ET 428
ET 428 Energy Efficiency in Refrigeration Systems Show data sheet (pdf file) Print page
Technical Description

  The efficient use of energy in refrigeration is an important topic. A higher power requirement is implemented in industry by connecting several small compressors in parallel. This permits the optimum adaptation to the power requirement by adding and removing compressors. ET 428 includes three compressors connected in parallel for this purpose which can be switched on or off via a controller.
  The components of a refrigeration circuit with three compressors are arranged clearly in the trainer. A glycol-water circuit with pump and tank with heater serves as cooling load at the evaporator. An internal heat exchanger in the refrigeration circuit allows for the refrigerant supercooling to be examined for process efficiency. The quantitative analysis of the efficiency takes place using an energy balance in the glycol-water circuit and by measuring the electrical power of the compressors.
  To protect the three compressors, the refrigeration circuit is equipped with a combined pressure switch for the delivery and intake sides. To ensure a secure oil supply to the three compressors, an oil separator is provided on the delivery side of the compressors. The separated oil is returned to the compressors on the intake side. The oil is monitored through sight glasses in the respective lines.
  Relevant measured values are recorded by sensors. The measured values can be read on digital displays. At the same time, the measured values can also be transmitted directly to a PC via USB. The data acquisition software is included.
  The well-structured instructional material sets out the fundamentals and provides a step-by-step guide through the experiments.


Learning Objectives / Experiments

- Variables affecting energy efficiency
  * controller parameters
  * refrigerant supercooling 
- Interconnected operation of compressors
- Operation of a multicompressor controller
- Methods for returning oil in a multicompressor

  refrigeration system
- Representation of the thermodynamic cycle in the

  log p-h diagram


* Refrigeration system with 3 compressors in

  interconnected operation1
* Ideal adaptation to the power requirement by adding

  and removing individual compressors1
* Industrial multicompressor controller to add and

  remove the individual compressors1
* Add-on heat exchanger for refrigerant supercooling1
* Monitoring of the lubrication oil transport in the

  refrigeration circuit

Alternative products
ET 165 -- Refrigeration System with Open Compressor
ET 422 -- Capacity Control and Faults in Refrigeration Systems
ET 426 -- Capacity Control in Refrigeration Systems

[1] Refrigeration system in multicompressor operation to investigate energy efficiency
[2] Refrigeration circuit with 3 compressors connected in parallel, condenser, thermostatic expansion valve and coaxial coil heat exchanger as evaporator
[3] Heat exchanger for refrigerant supercooling can be added via valves
[4] Glycol-water circuit includes pump and tank with heater serving as cooling load at the evaporator
[5] Multicompressor controller for the parallel operation of the compressors
[6] Separation of oil from the refrigerant on the delivery side and return to the intake side of the compressors
[7] Fan at the condenser with adjustable speed
[8] LabVIEW software for data acquisition via USB under Windows XP or Windows Vista
[9] Refrigerant R134a, CFC-free

Technical Data
3 compressors
- refrigeration capacity: each 1584W at -10C/55C
- power consumption: each 1156W at -10C/55C
Condenser with fan
- capacity: 4100W
- air flow: 1250m/h
Coaxial coil heat exchanger capacity
- 4kW at ΔT=9K; 0,6m/h glycol-water mixture
Glycol-water mixture pump
- max. flow rate: 5m/h
- max. head: 6m
Heater power: 3kW
- glycol-water mixture: 23L
- refrigeration circuit receiver: 5,8L
Measuring ranges
- temperature: 4x 0...100C, 4x -100C...100C
- pressure: 1x -1...9bar, 1x -1...24bar
- flow rate: 1x 1..25L/min
- compressor power: 0...4995W
Dimensions and Weight
l x w x h: 1800x700x1900mm
Weight: approx. 300kg
Required for Operation
400V, 50/60Hz, 3 phases
Scope of Delivery
1 trainer
1 LabVIEW software CD + USB cable
1 set of instructional material
Order Details

061.42800  ET 428  Energy Efficiency in

                                Refrigeration Systems

© 2005 G.U.N.T. Gerätebau GmbH