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ET 351C Thermodynamics of the Refrigeration Circuit
Education / GUNT Hamburg / Thermal Engineering and HVAC / Refrigeration and Air Conditioning Technology /

In this trainer, great care was taken to make the thermodynamic processes in the refrigeration system as transparent as possible. The capacities of compressor, evaporator and condenser can be measured. Pressure and temperature measuring points are provided at all the relevant locations to also allow for the pressure and heat losses in a refrigeration system to be investigated in detail. 
  The refrigeration circuit of ET 351C contains an open compressor with variable speed, a water-cooled condenser, a thermostatic expansion valve and an electrically heated evaporator.
  The compressor is driven via a pendulum bearing motor with frequency converter for speed adjustment. A force transducer permits the measuring of the drive torque. Using the speed the mechanical drive power of the compressor can thus be determined. The electrical heating capacity of the evaporator can be freely adjusted and is displayed. The condenser capacity is measured via the cooling water flow.  
  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 software allows for the process to be represented in the log p-h diagram and displays the key characteristic variables of the process, e.g. compressor pressure ratio and coefficient of performance. 

  The well-structured instructional material sets out the fundamentals and provides a step-by-step guide through the experiments.


Learning Objectives / Experiments

- Cyclic process in the log p-h diagram
- Comparison of the real cyclic process and

  the ideal cyclic process
- Energy balances at the evaporator and condenser
- Calculation of the motor power via speed and

- Determination of losses
- Calculation of the coefficient of performance
- Operating behaviour under load 
- Non-steady-state operating behaviour

[1] Thermodynamic investigation of a refrigeration circuit
[2] Refrigeration circuit with open compressor, water-cooled condenser, thermostatic expansion valve and electrically heated evaporator
[3] Compressor drive with speed-controlled motor via V-belt
[4] Motor on pendulum bearing for torque measurement
[5] Tube evaporator with adjustable heater as cooling load
[6] Water-cooled coaxial coil heat exchanger as condenser
[7] Displays for temperature, pressure, flow rate, speed, torque and power at the equipment
[8] LabVIEW software for data acquisition via USB under Windows XP or Windows Vista
[9] Refrigerant R134a, CFC-free
Technical Data

Open compressor 
- refrigeration capacity: approx. 550W (at a speed

  of 500min-1 and -10/20°C)
- motor: 370W, 1500min-1 
Heater: 2x 750W
- capacity: 1300W


Measuring ranges
- temperature: 9x -30...100°C
- pressure: 2x -1...9bar, 2x -1...15bar
- torque (compressor): 0...10Nm
- speed (compressor): 0...600min-1
- power consumption (compressor): 0...2000W
- power (heater): 0...2000W
- flow rate (water): 0...70g/s
- flow rate (refrigerant): 0...15g/s

Dimensions and Weight
l x w x h: 1520x790x1760mm
Weight: approx. 120kg
Required for Operation
230V, 50/60Hz, 1 phase
Water connection
Scope of Delivery

1 trainer

1 hose

1 LabVIEW software CD + USB cable

1 set of instructional material

Order Details

061.351C0  ET 351C  Thermodynamics of the Refrigeration Circuit