EVAPORATOR CONTROL WITH ELECTRONIC EXPANSION VALVE
The control of refrigeration units such as chiller cabinets, refrigerated display cases and freezers is a key topic in commercial
refrigeration. The control aims at safeguarding a high level of food quality with simultaneous energy-efficient operation.
The refrigeration controller continuously monitors the operation of the components and issues an alarm signal should errors occur. The controller is programmed via a data cable using a programming device. This allows for adjustments of the thermostat function, daytime/night-time operation, the defrosting function, energy saving functions and safety functions. In the simulation software the outside temperature is entered, the refrigerant selected and the door of the freezer opened or closed. In the "time graph" menu, the operating states of the individual components are displayed and the temperature and pressure graphs recorded.
Additional real components, such as expansion valve and pressure and temperature sensors, are used for demonstration purposes and increase the practical relevance.
The well-structured instructional material sets out the fundamentals and provides a step-by-step guide through the experiments.
Learning Objectives / Experiments
Modern refrigeration controller with electronic
Expansion valve
Functional principle of the controller
Thermostat function
Daytime and night-time operation
Operation with open and closed freezer
Defrost functions
Safety functions
Alarm functions
Monitoring of the components
Controller programming
Fault finding
Specification
Experimental unit from the practical series for the training of mechatronics engineers for refrigeration
Investigation and programming of an industrial refrigeration controller in the example of a freezer
Simulation of the freezer by way of software
Schematic on the front panel with lamps to indicate the operating states of the actuators
Programming of the refrigeration controller using a programming device
Simulated freezer with compressor, electronic expansion valve, fan, electric defrost heater for the evaporator, frame heating, pressure and temperature sensors
Real freezer components for demonstration purposes: 1 electronic expansion valve, 1 pressure sensor, 2 temperature sensor
Software for simulation via USB under Windows Vista or Windows 7
Technical Data
Functions of the refrigeration controller
Thermostat function
Daytime/night-time operation
Defrost functions
Messages and alarms
Fan operation
Energy saving functions
Safety functions
Simulated sensors
Air temperature upstream of the evaporator
Air temperature downstream of the evaporator
Evaporator surface temperature
Refrigerant temperature upstream of the compressor