Heat Transfer, Refrigeration and Air Conditioning Questions

• In aqua-ammonia and Lithium-bromide water absorption refrigeration systems, the refrigerants are respectively
• The total radiation from a black body per second per unit area is __________ fourth power of the absolute temperature. This statement is known as Stefan-Boltzmann law.
• According to Dalton's law of partial pressures, (where pb = Barometric pressure, pa = Partial pressure of dry air, and pv = Partial pressure of water vapour)
• During a refrigeration cycle, heat is rejected by the refrigerant in a
• The critical radius is the insulation radius at which the resistance to heat flow is
• In free convection heat transfer transition from laminar to turbulent flow is governed by the critical value of the
• The humidity ratio or specific humidity is the mass of water vapour present in
• In case of solids, the heat transfer takes place according to radiation.
• Which of the following represents a heat pump?
• The condition of refrigerant after leaving the compressor and before entering the condenser is superheated vapour.
• The heat transfer takes place according to
• The amount of radiation mainly depends upon the
• The temperature of ammonia after compression in a vapour compression system is
• The coefficient of performance of Heat Pump is always __________ one.
• Degree of saturation or percentage humidity is
• The subcooling in a refrigeration cycle
• Fourier's law of heat conduction is (where Q = Amount of heat flow through the body in unit time, A = Surface area of heat flow, taken at right angles to the direction of heat flow, dT = Temperature difference on the two faces of the body, dx = Thickness of the body, through which the heat flows, taken along the direction of heat flow, and k = Thermal conductivity of the body)
• The process of heat transfer from a hot body to a cold body, in a straight line, without affecting the intervening medium, is called radiation.
• The by-pass factor for a cooling coil
• The formation of frost on cooling coils in a refrigerator