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You Are On Multi Choice Question Bank SET 1431

71551. The heat is transferred by conduction, convection and radiation in





71552. A thermostatic expansion valve in a refrigeration system





71553. The temperature rise, between the condenser outlet and expansion valve in ammonia vapour compression system, should be as low as possible.



71554. The ratio of the actual mass of water vapour in a unit mass of dry air to the mass of water vapour in the same mass of dry air when it is saturated at the same temperature and pressure, is called





71555. For unsaturated air, the dew point temperature is __________ wet bulb temperature.




71556. During dehumidification process, __________ remains constant.





71557. Pressure of water vapour is given by


71558. Emissivity of a body will be equal to its absorptivity at all temperatures.



71559. R-12 is generally preferred over R-22 in deep freezers since





71560. The temperature of air recorded by a thermometer, when its bulb is surrounded by a wet cloth exposed to the air, is called





71561. During sub-cooling, sensible heat from a liquid refrigerant is removed.



71562. The expression is used for calculating relative humidity.



71563. If the energy radiated per second per sq. cm. of the surface for wave lengths lying between λ, and λ + dλ is represented by (eλ.dλ), then eλ is called





71564. Dry bulb temperature is the temperature of air recorded by a thermometer, when





71565. In a spray washing system, if the temperature of water is higher than the dry bulb temperature of entering air, then the air is





71566. A valve which maintains a constant degree of superheat at the end of the evaporator coil, is called





71567. The atmospheric air at dry bulb temperature of 15°C enters a heating coil maintained at 40°C. The air leaves the heating coil at 25°C. The by-pass factor of the heating coil is





71568. An infinite parallel planes with emissivities e1 and e2, the interchange factor for radiation from surface 1 to surface 2 is given by



71569. The final relative humidity of the air during cooling and dehumidification is generally __________ than that of entering air.



71570. The emissivity of a polished silver body is __________ as compared to black body.





71571. In a pressure enthalpy chart, the space between the saturated liquid line and saturated vapour line, represents sub-cooled liquid region.



71572. R-11 has the highest critical point temperature.



71573. The ratio of heat extracted in the refrigerator to the workdone on the refrigerant is called





71574. Air refrigerator works on





71575. The reciprocating refrigerant compressors are very suitable for





71576. The boiling point of carbon dioxide is





71577. The mass of water vapour present in __________ is called absolute humidity.





71578. The relative coefficient of performance is equal to



71579. The cooling system used for supersonic aircrafts and rockets is





71580. The desirable property of a refrigerant is





71581. The humidification process, on the psychrometric chart is shown by





71582. The colour of the flame of halide torch, in case of leakage of freon refrigerant, will change to





71583. The wet bulb depression indicates __________ humidity of the air.




71584. The refrigerant widely used in domestic refrigerators is





71585. When absorptivity (α) = 1, reflectivity (ρ) = 0 and transmittivity (τ) = 0, then the body is said to be a





71586. Prandtl number (PN) is given by PN = μ.cp/k.



71587. In a vapour compression system, the condition of refrigerant before passing through the condenser is





71588. A composite slab has two layers of different materials with thermal conductivities k1 and k2. If each layer has the same thickness, then the equivalent thermal conductivity of the slab will be



71589. The critical temperature is the temperature





71590. The evaporator changes the low pressure liquid refrigerant from the expansion valve into





71591. For air conditioning the operation theatre in a hospital, the percentage of outside air in the air supplied is





71592. In case ofsensible cooling of air, the coil efficiency is given by




71593. The mass of water vapour present in 1 kg of dry air, is called humidity ratio.



71594. In a vapour compression refrigeration system, a throttle valve is used in place of an expander because





71595. The unit of overall coefficient of heat transfer is





71596. Most thermostatic expansion valves are set for a superheat of





71597. For large tonnage (more than 200 TR) air-conditioning applications, the compressor recommended is





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