At what point in a vapor compression cycle does the minimum temperature happen ?
Show answer Hide answer
Answer: B. evaporator
Explanation
The minimum temperature in a vapor compression cycle occurs inside the evaporator. Refrigerant absorbs heat at low pressure in the evaporator, maintaining the lowest temperature. Expansion valves drop liquid pressure, initiating this cold low temperature boiling process. Vapor compression cycles manipulate refrigerant pressure to control boiling and condensing points. The evaporator acts as a heat exchanger where low pressure liquid flashes into cold vapor. Compressors then raise both the pressure and temperature of the refrigerant vapor stream.
Understanding temperature profiles helps HVAC technicians diagnose poor cooling performance issues. The low evaporator temperature enables heat transfer from the refrigerated space into the system. Insulation on suction lines prevents unwanted ambient heat gain after the evaporator stage. The condenser operates at high temperatures to reject heat to the surrounding environment. Compressors increase refrigerant temperature significantly during the mechanical compression process. Expansion valves experience temperature drops but do not maintain the cycle minimum point.
- Subject
- Engineering
- Category
- Mechanical Engineering
- Topic
- —
- Difficulty
- medium
Related questions
Q1. Which of the following does NOT constitute a desirable characteristic for a working refrigerant_________________?
Show answer Hide answer
Answer: C. good electrical conductor
A good working refrigerant must be a poor electrical conductor to prevent electrical short circuits. Hermetic compressors submerge motor windings directly in the refrigerant and oil mixture. Conductive refrigerants would...
Q2. Household domestic refrigerators typically employ which type of compressor____________________?
Show answer Hide answer
Answer: D. piston type reciprocating
Household domestic refrigerators typically employ a hermetically sealed, miniature reciprocating piston-type compressor. This sealed design encloses both the electric motor and compressor mechanism within a welded steel...
Q3. Incorporating under-cooling (sub-cooling) into a refrigeration cycle leads to_________________?
Show answer Hide answer
Answer: A. increases COP
Sub-cooling the liquid refrigerant increases the net refrigeration effect without increasing the compression work, thereby increasing the COP. By lowering the liquid enthalpy entering the expansion valve, each kilogram o...
Q4. The maximum temperature within a vapor compression cycle is found at____________________?
Show answer Hide answer
Answer: E. compressor discharge
The maximum temperature in a vapor compression cycle occurs at the compressor discharge. Mechanical compression adds work energy, raising the pressure and temperature of the refrigerant vapor. Superheated high-pressure g...
Q5. What is typically the COP value in a vapor compression cycle__________________?
Show answer Hide answer
Answer: B. always more than unity
The coefficient of performance in a vapor compression cycle is always greater than unity because heat extracted exceeds work. Refrigeration systems pump heat by consuming a relatively small amount of electrical work comp...
Q6. Ideal steam reheating takes place at a constant __________________?
Show answer Hide answer
Answer: C. pressure
Ideal steam reheating takes place at a constant pressure inside the reheater tubes.