TENNEY ENVIRONMENTAL
Tenney Junior Test Chambers: Models TJR and TUJR, W942, or WF4
Page 23
TJR Machinery Compartment
TU-JR Machinery Compartment
Basic System Description:
This is a multiple refrigeration system consisting of a low stage and a high stage system. These systems are
integrated to efficiently provide very low temperature levels. This is achieved by utilizing a cascade
condenser in the low stage, where low stage refrigerant is cooled and condensed by the high stage
refrigerant. The cooled low stage refrigerant now has greater cooling capacity in the chamber evaporator
coil. An air-cooled condenser is used in the high stage.
Capillary Tube Control Description:
This system employs capillary tube type refrigerant control. A long length of seamless copper tubing with a
small internal diameter is used to feed the evaporator coil. The tube acts as an automatic throttle in
controlling refrigerant pressure and flow to the evaporator. With the compressor running, a high pressure is
maintained on the inlet to the capillary tube, and a low pressure is maintained in the evaporator. The
pressures will balance when the compressor is turned off. This places a low starting load on the compressor
motor when turned back on. A fine filter or filter-drier is provided at each capillary tube inlet to remove
moisture and dirt from the refrigerant.
Low Stage Description
The low stage system includes the compressor, the cascade condenser, an expansion tank, and the
evaporator coil located in the chamber conditioning section.
Refrigerant flow in the low stage is from the compressor as a hot compressed gas and then through a
desuperheater where most of the heat of compression is removed. The desuperheater is part of the high
stage air cooled condenser. As a cooled gas, it then flows to the cascade condenser where it condenses to
10.0 CASCADE REFRIGERATION SYSTEM
ir - Cooled Condense
Compressors
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