A Thermopane window of area 3.1 m2 is constructed of two layers of glass, each 3.9 mm thick separated by an air space of 2 mm. If the inside is at 17◦C and the outside is at −24◦C, what is the heat loss through the window? The thermal conductivity of glass is 0.8 W/m · ◦ C and of air is 0.0234 W/m · ◦ C . Answer in units of kW.

Arigid tank contains 10 kg of air at 137 kpa (abs) and 21°c. more air is added to the tank until the pressure and temperature rise to 242 kpa (abs) and 32°c, respectively. determine the amount of air added to the tank. [r-0.287 kj/kg k]

Apinion having 30 involute teeth of 6,5 module rotates at 220 r/min and transmits 2 kw to a gear wheel having 70 teeth; the addendum on both wheels is 4 of the circular pitch and the angle of obliquity is 200. determine; 3.1 the lengths of the path of approach and the arc of approach 3.2 the normal force between the teeth at an instant when there is only one pair of teeth in contact

Aheat pump with refrigerant-134a as the working fluid is used to keep a space at 25°c by absorbing heat from geothermal water that enters the evaporator at 500c at a rate of 0.065 kg/s and leaves at 40°c. the refrigerant enters the evaporator at 20°c with a quality of 23 percent and leaves at the inlet pressure as saturated vapor. the refrigerant loses 300 w of heat to the surroundings as it flows through the compressor and the refrigerant leaves the compressor at 1.4 mpa at the same entropy as the inlet. determine: (a) the degrees of subcooling of the refrigerant in the condenser, b)-the mass flow rate of the refrigerant . (c) the heating load and the cop of the pump, and d)-the theoretical minimum power input to the compressor for the same heating load.