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 ET 351C Thermodynamics of the Refrigeration Circuit
 Technical Description

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 evaporator heated by a hot water circuit.
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 power of the hot water circuit 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

torque
- determination of losses
- calculation of the coefficient of performance

 Features

* Compression refrigeration system for

thermodynamic investigations1
* Indirectly heated evaporator and water-cooled

condenser1
* Open compressor with pendulum bearing drive

motor for torque measurement

 Specification [1] thermodynamic investigation of a refrigeration circuit[2] refrigeration circuit with open compressor, water-cooled condenser, thermostatic expansion valve and indirectly heated evaporator[3] compressor drive with speed-controlled motor via V-belt[4] motor on pendulum bearing for torque measurement[5] tube evaporator with hot water circuit 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] GUNT software for data acquisition via USB under Windows Vista or Windows 7[9] refrigerant R134a, CFC-free Technical Data Open compressor - refrigeration capacity: approx. 550W (at a speed  of 500min-1 and -10/20°C)- motor: 550W, 1.400min-1 Heater: 1x 1.000WCondenser- capacity: 1.300W Measuring ranges- temperature: 9x -30...100°C, 1x 0...100°C- pressure: 1x -1...9bar, 1x -1...24bar, 2x -1...15bar- torque (compressor): 0...10Nm- speed (compressor): 0...2.500min-1- power consumption (compressor): 0...1.125W- power (heater): 0...1.125W- flow rate (water): 5...70g/s- flow rate (refrigerant): 0...0,5L/min Dimensions and Weight LxWxH: 1.520x790x1.760mmWeight: approx. 120kg Required for Operation 230V, 50/60Hz, 1 phaseWater connection Scope of Delivery 1 trainer1 set of hoses, 1 manual pump1 GUNT software CD + USB cable1 set of instructional material Order Details 061.351C0  ET 351C  Thermodynamics of the                                     Refrigeration Circuit