Refrigerating Systems. Capillaries

The capillary tube is the simplest type of device control the refrigerant flow and can be used instead of the expansion valve. The capillary tubes of small diameter pipes, which flows refrigerant in the evaporator. These devices, which are widely used in small hermetic type refrigeration systems (up to 30 kW of power), to reduce the condensing pressure on the evaporating pressure in the copper tube small internal diameter (0.4РІР‚3 mm in diameter and 1.5-5 m in length), maintaining a constant pressure boiling independently of the refrigeration load changes. The tubes are used for the transmission of pressure from the sensing bulb some temperature control device operating element. Capillary tube can be built as part of the heat exchanger, particularly in domestic refrigerators.

With capillary tube, the tube length is comparable with the performance of the compressor. Other considerations when determining capillary tube size include the efficiency of the condenser and evaporator size. Capillary tube are most effective when used in low-power systems.

Fig. 3.23 shows an excellent scheme practical vapour compression refrigeration system control devices.

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