Mechanical Engineering :: Heat Transfer,Refrigeration and Air Conditioning
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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)
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The relative humidity is defined as
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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)
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The heat transfer by conduction through a thick sphere is same as through a thick cylinder.
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In aqua-ammonia and Lithium-bromide water absorption refrigeration systems, the refrigerants are respectively
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As relative humidity decreases, the dew point temperature will be __________ wet bulb temperature.
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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.
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Reynolds number (RN) is given by (where h = Film coefficient, l = Linear dimension, V = Velocity of fluid, k = Thermal conductivity, t = Temperature, ρ = Density of fluid, cp = Specific heat at constant pressure, and μ = Coefficient of absolute viscosity)
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The optimum effective temperature for human comfort is
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A.
the mass of water vapour present in 1 m3 of dry air
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B.
the mass of water vapour present in 1 kg of dry air
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C.
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.
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D.
the ratio of actual mass of water vapour in a given volume of moist air to the mass of water vapour in the same volume of saturated air at the same temperature and pressure
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