A 4-m x 5-m x 6-m room is to be heated by a baseboard resistance heater. It is desired that the resistance heater be able to raise the air temperature in the room from 7°C to 25°C within 15 minutes. Assuming no heat losses from the room and an atmospheric pressure of 100 kPa, determine the required power rating of the resistance heater Assume constant specific heats at room temperature

A Carnot heat engine operates between reservoirs at 30°C and 290°C. Determine the efficiency of the engine as a percentage to 3 significant figures.

Explain the concept of entropy and its significance in the second law of thermodynamics. Discuss how entropy changes influence the efficiency of thermal systems.

A-C line Liquid R-134a A rigid container containing 6.6 kg of saturated liquid R-134a at 24°C is used to fill an air-conditioning system. A valve is opened and allows liquid R-134a to escape the tank into the A-C line until only 0.49 kg of R-134a remains in the tank, at which point the valve is closed. During the process, heat transfer is allowed to occur to maintain the tank temperature at 24°C. What is the quality of the refrigerant inside the tank at the end of the process? What is the total heat transfer for this process? KJ