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 ET 432 Behaviour of a Piston Compressor
 Technical Description

Smaller refrigeration systems usually have a piston compressor. Piston compressors are positive displacement machines. These differ in their characteristics decisively from flow equipment which include the turbo compressors that are common in very large systems.
In piston compressors the flow rate is mainly dependent on the displaced volume and speed. Due to the unavoidable dead space the flow rate drops with increasing pressure ratio. Because the flow rate is a measure for the refrigeration capacity of the refrigeration system, the properties of the compressor are important for the whole system.
In this trainer a commercial open refrigerant compressor is operated in an open process with air. The inlet and outlet pressures and thus the pressure ratio can be adjusted via valves in wide ranges. The drive via a frequency converter permits variable speeds. Pressures, temperatures, electric power consumption, speed and torque are recorded and displayed at the equipment. The compressor efficiency is calculated from the electrical and mechanical power.
The well-structured instructional material sets out the fundamentals and provides a step-by-step guide through the experiments.

Learning Objectives / Experiments

- Determine characteristic variables of a piston

compressor during experiments
- Record of the pressure/volume flow characteristic
- Determination of the volumetric efficiency at different

intake pressures, pressure ratios and speeds
- Determination of the isothermal compressor

capacity
- Measurement of the mechanical and electrical

power consumption in dependence of the intake

pressure and pressure ratio
- Determination of the mechanical efficiency and the

overall efficiency

 Features

* Open 2-cylinder piston compressor from

refrigeration1
* Record of the pressure/volume flow characteristic1
* Measurement of intake volume and pressure ratio1
* Determination of volumetric and mechanical

efficiency

 Specification [1] Experimental unit for piston compressor from refrigeration [2] Open process with air[3] Typical open 2-cylinder compressor[4] Drive via asynchronous motor with frequency converter for speed adjustment[5] Inlet pressure and outlet pressure (pressure ratio) adjustable via valves[6] Instruments: manometer, flow meter, temperature sensor, speed, torque (via force), digital power indication Technical Data Compressor- speed: 480...975min-1- number of cylinders: 2- stroke: 26mm- borehole: 35mm- displaced volume: 50cm³- max. intake capacity: 49L/min- max. pressure: 20barDrive motor power: 370W Measuring ranges- torque: 0...5Nm- speed: 0...3000min-1- electric power: 0...1000W- temperature: 0...100°C- pressure: -1...9bar / -1...24bar- flow rate: 8...80L/min Dimensions and Weight l x w x h: 1400x790x1750mmWeight: approx. 150kg Required for Operation 230V, 50Hz, 1 phase Scope of Delivery 1 trainer1 set of instructional material Order Details 061.43200  ET 432  Behaviour of a Piston                                  Compressor