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Products  |  Thermal Engineering and HVAC  |  Refrigeration and Air Conditioning Technology  |  ET 422
ET 422 Capacity Control and Faults in Refrigeration Systems Show data sheet (pdf file) Print page
Technical Description

  The efficient control of the capacity and temperature in refrigeration systems is an important topic in refrigeration technology. With ET 422 different methods of capacity control can be investigated.
  The components of a refrigeration circuit with refrigeration and freezing chambers are arranged clearly in the trainer. Solenoid valves enable the separate or parallel operation of the evaporators in the two chambers. The circuit is equipped with a capacity controller, a start-up controller and a combined pressures switch for the delivery and intake sides of the compressor. One heat exchanger each in the inlet of the two evaporators enables the supercooling of the refrigerant to be investigated for the efficiency of the process. The refrigeration capacity of the two individual chambers is controlled by a thermostat. The refrigeration chamber also features an evaporation pressure controller.
  There are two defrosting methods for the freezing chamber: an electric defrost heater and a hot gas defrosting where hot refrigerant is fed directly from the compressor in the opposite direction through the evaporator.
  The simulation of 12 different faults, such as e.g. faulty valves or  clogged pipes, is activated using a touch panel PC.
  Relevant measured values are transmitted directly to the touch panel PC and analysed. The software enables e.g. the representation of the cycle in the log p-h diagram. 

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


Learning Objectives / Experiments

- familiarisation with the key devices for changing the

  refrigeration capacity

  * thermostat
  * capacity controller
  * start-up controller
  * evaporation pressure controller

  * condensation pressure controller
- fault finding in refrigeration system components
- effect of refrigerant supercooling
- familiarisation with defrosting methods
  * electric defrost heater
  * hot gas defrosting
- representation of the thermodynamic cycle in the

  log p-h diagram


* Practice-oriented model of a commercial

  refrigeration system1
* Refrigeration and freezing chamber to investigate

  different methods for capacity control1
* Simulation of 12 faults1
* 2 defrosting methods for freezing chamber

Alternative products
ET 405 -- Heat Pump for Cooling and Heating Operation
ET 412C -- Refrigeration System with Refrigeration and Freezing Chamber
ET 426 -- Capacity Control in Refrigeration Systems
ET 428 -- Energy Efficiency in Refrigeration Systems
ET 422 Capacity Control and Faults in Refrigeration Systems

[1] investigation of a refrigeration system with refrigeration and freezing chambers
[2] refrigeration circuit with compressor, condenser, capacity controller, start-up controller, combined pressure switch and 2 evaporators in insulated chambers
[3] each chamber with solenoid valve, thermostat, thermostatic expansion valve, fan and heat exchanger for refrigerant supercooling
[4] refrigeration chamber with evaporation pressure controller
[5] freezing chamber with electric defrost heater and hot gas defrosting
[6] separate or parallel operation of the chambers via solenoid valves
[7] simulation of 12 faults
[8] touch panel PC for fault activation, data acquisition, evaluation and representation in the

log p-h diagram
[9] refrigerant R404a


Technical Data

- refrigeration capacity: 2.440W at -10/30C
Condenser with fan
- air flow: 570m/h
Evaporator transfer areas
- refrigeration chamber: 1,12m
- freezing chamber: 1,88m
Electric defrost heater: approx. 125W
Capacity controller: 0,2...6bar
Start-up controller: 0,2...6bar
Thermostat: 2x -25...15C
Evaporation pressure controller: 0...5,5bar
Measuring ranges
- temperature: 6x -50...50C; 5x 0...100C
- pressure: 3x -1...12,5bar; 2x -1...24bar 
- flow rate: 2x 1.5...22,5L/h
- compressor power consumption: 0...5kW


Dimensions and Weight
LxWxH: 2.420x780x1.900mm
Weight: approx. 280kg
Required for Operation
400V, 50Hz, 3 phases or 230V, 60Hz/CSA, 3 phases
Scope of Delivery

1 trainer

1 set of instructional material

Order Details

061.42200  ET 422  Capacity Control and Faults in

                                 Refrigeration Systems

© 2005 G.U.N.T. Gerätebau GmbH