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ET 412C

- Refrigeration system with 2 different evaporation pressures
- Simulation of 18 faults


Technical Description

Identifying faults in refrigeration systems requires comprehensive knowledge This knowledge also includes the design and purpose of the individual components. ET 412C helps to acquire this knowledge.

The components of a refrigeration circuit with refrigeration and freezing chambers are arranged clearly in the trainer. Solenoid valves enable the individual or parallel operation of the evaporators in the two chambers. The circuit is equipped with a combined pressure switch for the delivery and intake side of the compressor. The refrigeration chamber features an evaporation pressure controller. The effect of the evaporation pressure controller on the overall process is being examined. An inner heat exchanger in the inlet of the two evaporators is used for supercooling the refrigerant to increase the efficiency of the process. At the same time the intake gas is superheated.

An electric defrost heater is available to defrost the freezing chamber. The simulation of 18 different faults, e.g. faulty solenoid valves or faulty relays, is provided for.

The process schematic at the trainer offers a quick overview. Signal lamps in the process schematic indicate the operating state of selected components.

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 most important pressures are additionally indicated with manometers directly at the trainer. The software enables the representation of the cyclic process 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

- design and components of a refrigeration system with 2 evaporators 
- components and their functions
  * compressor, condenser, evaporator
  * thermostatic expansion valve
  * evaporation pressure controller
  * pressure switch
  * electric defrost heater 
- thermodynamics of the refrigeration cycle
  * effect of refrigerant supercooling
  * representation of the thermodynamic cycle in the log p-h diagram
  * determination of important characteristic variables
    * coefficient of performance
    * refrigeration capacity
    * compressor work
- fault finding in refrigeration system components



[1] investigation of a refrigeration system with refrigeration and freezing chambers
[2] refrigeration circuit with compressor, condenser and 2 evaporators with thermostatic expansion valve and evaporation pressure controller
[3] insulated freezing chamber with fan and electric defrost heater
[4] insulated refrigeration chamber with evaporation pressure controller
[5] heat exchanger for refrigerant supercooling
[6] individual or parallel operation of the chambers via solenoid valves
[7] simulation of 18 faults 
[8] GUNT software for data acquisition via USB under Windows Vista or Windows 7
[9] refrigerant R134a, CFC-free

Technical Data
- power consumption: 491W at 5/40°C
- refrigeration capacity: 1104W at 5/40°C
Condenser with fan
- volumetric air flow rate: 290m³/h
- transfer area: 1,5m²
Refrigeration chamber
- evaporator transfer area: 1,06m²
Freezing chamber
- evaporator transfer area: 2,42m²
- volumetric air flow rate, fan: 135m³/h
- electric defrost heater: approx. 150W
Evaporation pressure controller: 0...5,5bar
Measuring ranges
- temperature: 12x -50...120°C
- pressure: 1x -1...15bar, 3x -1...9bar, 3x -1...24bar
- power: 0...1125W
- flow rate: 1,5...23,5L/h
  Dimensions and Weight LxWxH: 2000x670x1900mm
Weight: approx. 210kg Required for Operation 230V, 50/60Hz, 1 phase or 120V, 60Hz/CSA, 1 phase

Scope of Delivery

1 trainer
1 GUNT software CD + USB cable
1 set of instructional material

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