work (W) is made of electrical work (We,in), paddle-wheel work (Wpw,in), and boundary work (Wb) and for a piston – cylinder setup with insulation, ‘Q’ zeroes out (since there would be ‘no heat transfer’ between the system and its surroundings).
Hot exhaust gases of an internal combustion engine are to be used to produce saturated water vapour at 2 MPa pressure. The exhaust gases enter the heat exchanger at 400C at a rate of 32 kg/min while water enters at 15C. The heat exchanger is not well insulated, and it is estimated that 10% of heat given up by the exhaust gases is lost to the surroundings. If the mass flow rate of the exhaust is 15 times that of water, determine:
An air-conditioning system involves the mixing of cold air and warm outdoor air before the mixture is routed to the conditioned room in steady operation. Cold air enters the mixing chamber at 5C and 105 kPa at a rate of 1.25 m3/s while warm air enters at 34C and 105 kPa. The air leaves the room at 24C. The ratio of the mass flow rates of the hot to cold air streams is 1.6. Using variable specific heats,