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Expansion Valve
The expansion valve provides a sharp decrease in the pressure of the liquid refrigerant. When the refrigerant is sprayed, which facilitates the process of evaporation. The expansion valve regulates the flow of refrigerant supplied to the evaporator. Refrigerant flow is governed by the size of the opening of the ball valve in the expansion valve. The quantity is regulated by the pressure balance opening R-134a on the diaphragm and the resultant force at the evaporator outlet pressure (PI) - to the lower part of the diaphragm and the spring force (Fs), acting on the ball valve. When PI is increased, the temperature of the temperature sensor near the diaphragm is increased, and Pd heated R-134a on the diaphragm - increases. When more than Pd PI + Fs, the diaphragm flexes downward and the shaft attached to the end of the rod of the temperature sensor, pushes down the ball valve, increasing the flow of refrigerant.
| Fig. 8.65. The operating principle of the expansion valve: 1 - the diaphragm; 2 - a temperature sensor; 3 - shaft; 4 - Ball valve; 5 - a spring; 6 - from the evaporator; 7 - to the evaporator; 8 - from the condenser; 9 - to the condenser; 10 - the spring force; 11 - Pressure HFC-134a; 12 - outlet pressure
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When the refrigerant temperature at the outlet of the evaporator decreases, PI + Fs becomes higher than Pd, the ball valve is raised and the flow rate of the refrigerant decreases.
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