Question 134Refrigeration/AC - 1st Asst/Chief70% to pass
The thermostatic expansion valve in a refrigeration system further opens when the diaphragm flexes downward. With all other conditions being the same, what single condition causes this?
AI Explanation
The correct answer is A) an increase in sensing bulb temperature.
The thermostatic expansion valve in a refrigeration system is designed to maintain a constant superheat at the evaporator outlet. When the sensing bulb temperature increases, the pressure inside the sensing bulb also increases, causing the diaphragm to flex downward and further open the thermostatic expansion valve. This allows more refrigerant to flow into the evaporator, increasing the cooling capacity and maintaining the desired superheat.
The other options are incorrect because: B) an increase in evaporator pressure would cause the diaphragm to flex upward and close the valve, C) a decrease in sensing bulb temperature would cause the diaphragm to flex upward and close the valve, and D) increasing the superheat setting would cause the diaphragm to flex upward and close the valve.
Related Questions
#132 In a refrigeration system, the pressure within the power element of a thermostatic expansion valve depends directly upon what factor? #133 Which of the following illustrated expansion valves is designed to maintain a constant evaporator pressure rather than a constant evaporator superheat? Illustration GS-RA-24 #135 In the illustrated refrigeration system, what is the proper name for the component labeled "A"? Illustration GS-RA-12 #136 The carbon seal ring of a refrigeration compressor crankshaft mechanical seal is held in position against the stationary ring face by using what device? #137 The safety heads of most large reciprocating compressors used in refrigeration systems are held in place by what means?