Test: RAC Level - 1
25 Questions MCQ Test Mechanical Engineering SSC JE (Technical) | Test: RAC Level - 1
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Which one of the following is correct relation between (COP)HP and (COP)R
A heat pump operating based on a reversed carnot cycle between temperature T1 and T2, where T1 is higher absolute temperature and T2 is lower absolute temperature then the COP of heat pump is
A refrigerator operating based on reversed carnot cycle between T1 and T2 where T1 is high temperature and T2 is lower temperature then COP of refrigerator is
Horse power and kW required per tonne of refrigeration is expressed as
Horse power per ton = 4.75?COP
1 kW/ton = 3.516/COP
The COP of a heat pump can be increased either by decreasing TH by ΔT or by increasing TL by ΔT. The new COP of the heat pump is
The coefficient of performance of a domestic refrigerator is __________ as compared to a domestic air-conditioner.
Which one of the following sequence is correct in vapour compression cycle
In a vapour-compression refrigeration cycle, if h1 and h2 denote the enthalpies at inlet and exit of the compressor respectively, h3 is the enthalpy at the exit of the condenser and h4 is the enthalpy at the inlet of the evaporator, the COP for the cycle is
In a domestic refrigerator, a capillary tube controls the flow of refrigerant from the
In a domestic refrigerator, a capillary tube controls the flow of refrigerant from the Expansion valve to the evaporator
In a vapour compression cycle, the refrigerant immediately after expansion valve is
Correct Answer :- b
Explanation : Useful superheating increases both the refrigeration effect as well as the work of compression. Hence the COP (ratio of refrigeration effect and work of compression) may or may not increase with superheat, depending mainly upon the nature of the working fluid. Even though useful superheating may or may not increase the COP of the system, a minimum amount of superheat is desirable as it prevents the entry of liquid droplets into the compressor
Correct Answer :- c
Explanation : In Electrolux refrigerator Ammonia evaporates in hydrogen.
The ammonia liquid leaving the condenser enters the evaporator and evaporates into the hydrogen at the low temperature corresponding to its low partial pressure. The mixture of ammonia and hydrogen passes to the absorber into which is also admitted water from the separator. The water absorbs the ammonia and the hydrogen returns to the evaporator. In the absorber the ammonia therefore passes from the ammonia circuit into water circuit as ammonia in water solution. This strong solution passes to the generator where it is heated and the vapor given off rises to the separator. The water with the vapor is separated out and a weak solution of ammonia is passed back to the absorber, thus completing the water circuit. The ammonia vapor rises from the separator to the condenser where it is condensed and then returned to the evaporator.
An important characteristic of absorption system of refrigeration is
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