The lower horizontal line segment on a refrigeration cycle pressure-enthalpy diagram represents_____________________?
Show answer Hide answer
Answer: B. evaporation of the refrigerant liquid
Explanation
The lower horizontal line segment on a pressure-enthalpy diagram represents refrigerant evaporation. Liquid refrigerant absorbs latent heat and transforms into vapor at constant pressure. Evaporator pressure and saturation temperature remain constant along this phase change line. Pressure-enthalpy charts graph thermodynamic properties used in refrigeration cycle analysis. Horizontal lines on PH diagrams represent constant pressure isobaric phase transitions. The vapor compression cycle appears as a closed loop on pressure-enthalpy coordinates.
Refrigeration engineers use pressure-enthalpy diagrams to calculate system cooling capacities. Analyzing PH curves helps technicians determine mass flow rates and compressor displacements. Diagnosing system faults requires plotting operating pressures on refrigerant property charts. Condensation of refrigerant vapor appears as the upper horizontal line on PH diagrams. Compression of vapor is represented by the nearly vertical sloped line on PH charts. Metering of liquid refrigerant appears as a vertical constant enthalpy throttling process line.
- Subject
- Engineering
- Category
- Mechanical Engineering
- Topic
- —
- Difficulty
- medium
Related questions
Q1. Refrigerant leaks occurring in a system charged with Freon are detected using____________________?
Show answer Hide answer
Answer: A. halide torch which on detection produces greenish flame lighting
Refrigerant leaks in systems charged with Freon are detected reliably using a halide torch connected to a gas source. In the presence of halogenated Freon gases, the torch flame changes color to a distinct bright green o...
Q2. The normal atmospheric boiling point temperature of ammonia is___________________?
Show answer Hide answer
Answer: C. – 33.3°C
The normal atmospheric boiling point of ammonia is approximately –33.3°C. At standard atmospheric pressure, liquid ammonia boils and absorbs latent heat at this specific sub-zero temperature. This thermal property makes...
Q3. Decreasing the condenser temperature while keeping the evaporator temperature constant will cause the refrigeration cycle COP to__________________?
Show answer Hide answer
Answer: A. increase
Decreasing the condenser temperature lowers the high-side pressure and work input, thereby increasing the COP of the refrigeration cycle. Lowering the condenser temperature reduces the compressor pressure ratio and decre...
Q4. Refrigeration in aeroplanes usually employs the following refrigerant___________________?
Show answer Hide answer
Answer: D. Air
Air conditioning and refrigeration systems in aeroplanes use plain air as the working refrigerant due to safety and weight. Using air eliminates the hazards associated with toxic or flammable chemical refrigerants inside...
Q5. Standard vapor compression refrigerators operate according to which thermodynamic cycle_________________?
Show answer Hide answer
Answer: E. Reversed Carnot
Standard vapor compression refrigerators operate on the reversed Carnot cycle as an ideal theoretical upper bound.
Q6. The saturation vapor pressure characteristics of a suitable refrigerant should be_________________?
Show answer Hide answer
Answer: B. higher than atmospheric pressure
A suitable refrigerant should have a saturation vapor pressure higher than atmospheric pressure to prevent air leakage into the system. Operating above atmospheric pressure ensures that any minor flange or valve leak exp...