The concrete slab of a basement is 11 m long, 8 m wide, and 0.20 m thick. during the winter, temperatures are nominally 17°c and 10°c at the top and bottom surfaces, respectively. if the concrete has a thermal conductivity of 1.4 w/m · k, what is the rate of heat loss through the slab? if the basement is heated by a gas furnace operating at an efficiency of ηf = 0.9

Air enters a gas turbine with two stages of compression and two stages of expansion at 100 kpa and 17°c. this system uses a regenerator as well as reheating and intercooling – the intercooler returns the air to the inlet temperature. the pressure ratio across each compressor is 4 ; 300 kj/kg of heat are added to the air in each combustion chamber; and the regenerator operates perfectly while increasing the temperature of the cold air by 20°c. determine the system’s thermal efficiency. assume isentropic operations for all compressor and the turbine stages and use constant specific heats at room temperature. (0.378)