RA4 – Air-Conditioning Training Unit

 

RA4 – Air-Conditioning Training Unit

The RA4 is a standalone desktop refrigeration demonstrator based upon a vapour-compression refrigeration system (VCRS).

The most common refrigeration system used today, this is where the refrigerant undergoes phase changes to absorb and reject heat in a controlled manner.

Description

The RA4 is a standalone desktop refrigeration demonstrator based upon a vapour-compression refrigeration system (VCRS).

The most common refrigeration system used today, this is where the refrigerant undergoes phase changes to absorb and reject heat in a controlled manner.

The RA4 is designed to enable the student to gain an understanding of the fundamental components and operation of a refrigeration/ air-conditioning system. It is self contained and powered by a domestic 13amp supply.

The control panel comprises standard refrigeration gauges as used by a service technician. There are also indicators to show the status of the low-pressure, medium-pressure and high-pressure system safety switches. Indicators show the compressor running status.

Many of the components used are automotive, but the process is the same in vehicle, building services and refrigeration units. A DC compressor has been selected to provide drive, due to its low-voltage, low-noise operation against an automotive-style belt-driven compressor typical of high-current AC motors.

The principles shown relate to any form of heat exchanger that may use vapour-compression refrigerant within its process.

Technical Specifications

Features & Benefits

Features

  • Desktop vapour pressure air-conditioning system for training using R134a refrigerant
  • Hermetically sealed refrigerant compressor, with:
    – Integral low-voltage three-phase DC motor
    – Quiet and vibration-free operation
  • Condenser assembly to cool the refrigerant, incorporating:
    – Multi-pass condenser coil with aluminium fins
    – DC cooling fan
  • Evaporator assembly to cool and dehumidify the air, incorporating:
    – Thermal expansion valve
    – Evaporator coil with fins
    – Centrifugal air blower with three switched speeds
  • Three temperature displays indicating:
    – Air temperature before evaporator coil
    – Air temperature after evaporator coil
    – Refrigerant temperature in condenser coil
  • Built-in refrigerant Bourdon gauges on compressor suction and discharge lines with combined temperature and pressure scales
  • System includes receiver, filter/dryer, sight glass and high/lowpressure cut-outs for safe operation
  • High and low-pressure charging points enable operator training in addition to recharging
  • Demonstration/analysis of faults injected in the refrigerant circuit via three selector switches:
    – Blocked/faulty TXV (thermal expansion valve)
    – Blocked condenser pipework
    – Condenser fan fault
  • Three pressure switches with indicators showing low or high pressure under fault conditions and medium pressure in normal operation
  • No additional computer or diagnostic tools are required
  • Operated from mains power supply, but all components are 24V DC for improved operator safety
  • Comprehensive instruction manual with details of installation, operating procedures and sample teaching exercises including fault insertion and analysis

Benefits

  • Standalone desktop refrigeration system
  • Built-in temperature and pressure gauges as used by service technicians
  • Fault training through interchangeable fault condition switches
  • Low-voltage DC compressor and control circuit
  • Quiet operation for classroom use without the need for additional drive motors and noisy belt-driven compressors
  • No additional computers or diagnostic tools are required

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  • Demonstration of component function
  • Instrumented running conditions showing refrigeration pressures
  • Performance under running and fault conditions
  • Fault training through interchangeable fault condition switches

Electrical supply:

  • RA4-A: 220-240V / 1ph / 50Hz
  • RA4-B: 120 / 1ph / 60Hz
  • RA4-G: 220-240V / 1ph / 60Hz

PACKED AND CRATED SHIPPING SPECIFICATIONS

Volume: 0.5m³

Gross Weight: 90Kg

Length: 0.90m

Width: 0.50m

Height: 0.80m

  • RA4-A: 220-240V / 1ph / 50Hz
  • RA4-B: 120 / 1ph / 60Hz
  • RA4-G: 220-240V / 1ph / 60Hz

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