Sep 21, 2017
Table Top Showcases Refrigeration process
Freezer: desktop display cabinet evaporation temperature is too high or too low reason!
【Display cabinet】 evaporation temperature t0 refrigerant in the evaporator under a certain pressure boiling temperature of the vaporization. The evaporation temperature and the evaporation pressure are corresponding. The evaporation pressure p0 can be estimated from the suction pressure p1. In order to overcome the pressure drop, the evaporation pressure is generally greater than the suction pressure of 0.01 to 0.02 MPa, i.e., p0 = p1 + 0.01 to 0.02 MPa.
The evaporation temperature is determined by the requirements of the refrigeration process. Generally, when the air medium is a refrigerant, the evaporation temperature is 10 ℃ lower than the stock temperature. Application must be reasonable to select the evaporation temperature. Too low to select the evaporation temperature, will reduce the economic efficiency, the unit cooling capacity is small; too high to select the evaporation temperature, and can not meet the refrigeration process requirements.
For systems with capillaries as throttling elements, the change in evaporation temperature is only related to changes in condensation temperature and condensing pressure; for systems with expansion valves, the evaporation temperature can be controlled by adjusting the opening degree of the expansion valve. Evaporation temperature and pressure rise, the suction gas superheat is small, prone to wet stroke, the liquid hit the cylinder; evaporation temperature and pressure drop, the suction gas superheat is too large, so the compressor and exhaust temperature is too high.
Evaporation temperature is too high generally have the following reasons:
1, expansion valve open too large.
2, the desktop display cabinet compressor diaphragm broken or leaked.
3, the valve plate between the high and low pressure to penetrate.
4, the air in the refrigeration system.
5, too much refrigerant.
6, the heat load is too large.
7, the evaporator out of the pipe there are obstacles.
8, the condensation effect is not good.
9, the room doors and windows open too much or the destruction of the thermal layer, so that cold air escape, heat infiltration.
10. Compressor efficiency is low or the speed is too low.