DESCRIPTION

Technical Description

ET 915.02 is part of the HSI training system for refrigeration and air conditioning technology. In combination with the base unit ET 915 the operational model of a refrigeration system with refrigeration and freezing stage results. The model is plugged onto the base unit, secured using fasteners and connected with refrigerant hoses to become a complete refrigeration circuit. 

In refrigeration and freezing combinations evaporators are preferably connected in parallel. To increase the refrigeration capacity, evaporators are operated connected in series. Here different pressure levels in the evaporators can be used to obtain different temperature ranges for refrigeration or freezing. 

ET 915.02 includes two separate refrigeration chambers with evaporator and expansion elements. The evaporators can be optionally operated connected in series or in parallel. Two fans in the refrigeration chambers support the achievement of an even temperature distribution. With heaters cooling loads can additionally be simulated. One of the refrigeration chambers can optionally be operated with an expansion valve or a capillary tube as expansion element. The various operation modes are set via solenoid valves. An evaporation pressure controller permits in parallel operation the independent adjustment of the temperature level in the upper chamber. All components are clearly arranged on a panel. 

The operation of individual system components, here temperature control, fan, heater, compressor and solenoid valves, takes place via the software.

The software offers the option to simulate faults. Temperatures and pressures in the system are recorded by sensors and displayed dynamically in the software. The effect of parameter changes can be tracked online in the log p-h diagram. 

Fundamentals and individual components are represented in the educational software for ET 915.02. Performance assessments check the learning progress. With the aid of the authoring system further exercises and performance assessments can be created.

Learning Objectives / Experiments

- design and operation of a refrigeration system with two evaporators
- series and parallel connection of two evaporators
- familiarisation with the different expansion elements
  * operation with capillary tube
  * operation with expansion valve 
- operating behaviour under load
- refrigeration cycle in the log p-h diagram
- effect of the evaporation pressure
- fault simulation