misseylaLv10in Mechanical Engineering·10 Jul 2022An ammonia ice plant operates between a condenser temperature of 35°C and evaporator of -15°C. It produces 10 metric tons of ice per day from water at 30°C to ice at -5°C. Assuming simple saturation cycle, determine the horsepower of the motor if the adiabatic efficiency of the compressor n = 0.85 and mechanical efficiency n = 0.95. The specific heat of ice is 2.094 kJ/kg-°C and the latent heat is 335 kJ/kg. From the table for ammonia the following enthalpies are: condenser entrance = 1703 kJ/kg, exit = 366.1 kJ/kg; compressor entrance = 1443.9 kJ/kg, exit = 1703 kJ/kg.
misseylaLv10in Mechanical Engineering·10 Jul 2022An ammonia simple saturation cycle operates with a suction pressure of 291.6 kPa and a condenser pressure of 1204 kPa develops 15 tons of refrigeration. Determine the theoretical horsepower of the compressor. The following enthalpies have been found: condenser entrance = 1653 kJ/kg, exit = 346.6 kJ/kg; compressor entrance = 1450.2 kJ/kg, exit = 1653 kJ/kg.
misseylaLv10in Mechanical Engineering·10 Jul 2022A house that was heated by electric resistance heaters consumed 1200 kWh of electric energy in a winter month. If this house were heated instead by a heat pump that has an average performance factor, PF of 2.4, determine how much money the homeowner would be saved that month. Assume a price of 0.085 $/kWh for electricity.
misseylaLv10in Mechanical Engineering·10 Jul 2022A refrigeration system is to cool bread loaves with an average mass of 450 g from 22°C to – 10°C at a rate of 500 loaves per hour by refrigerated air. Taking the average specific and latent heats of bread to be 2.93 kJ/kg-°C and 109.3 kJ/kg, respectively, determine the product load.
misseylaLv10in Mechanical Engineering·10 Jul 2022An air-conditioning system is used to maintain a house at 75°F when the temperature outside is 95°F. The house is gaining the heat through the walls and windows at a rate of 1250 Btu/min, and the heat generation rate within the house from people, lights, and appliances amounts to 350 Btu/min. Determine the minimum power input required for this air-conditioning system
misseylaLv10in Mechanical Engineering·10 Jul 2022A household refrigerator with EER 8.0 removes heat from the refrigerated space at a rate of 90 kJ/min. Determine the rate of heat transfer to the kitchen air.
misseylaLv10in Mechanical Engineering·10 Jul 2022A Carnot refrigerator operates in a room in which the temperature is 25°C and consumes 2 kW of power when operating. If the food compartment of the refrigerator is to be maintained at 3°C, determine the rate of heat removal from the food compartment.
misseylaLv10in Mechanical Engineering·10 Jul 2022A thermoelectric refrigerator that resembles a small ice chest is powered by a car battery, and has a COP of 0.10. If the refrigerator cools a 0.350 L canned drink from 20°C to 4°C in 30 min, determine the average electric power consumed by the thermoelectric refrigerator.
misseylaLv10in Mechanical Engineering·10 Jul 2022A house is maintained at 22°C in winter by electric resistance heaters. If the outdoor temperature is 5°C, the second law efficiency of the resistance heaters is?
misseylaLv10in Mechanical Engineering·10 Jul 2022A water reservoir contains 100,000 kg of water at an average elevation of 60 m. The maximum amount of electric power that can be generated from this water is ?
misseylaLv10in Mechanical Engineering·10 Jul 2022A heat engine receives heat from a source at 1200 K at a rate of 500 kJ/s and rejects the wasted heat to a sink at 300 K. If the power output of the engine is 200 kW, the second law efficiency of this heat engine is?
misseylaLv10in Mechanical Engineering·10 Jul 2022A thermal power has a net power of 10 MW. The backwork ratio of the plant is 0.005. Determine the compressor work.
misseylaLv10in Mechanical Engineering·10 Jul 2022Air enters a turbojet engine at 200 m/s at a rate of 20 kg/s and exits at 800 m/s relative to the aircraft. The thrust developed by the engine is?
misseylaLv10in Mechanical Engineering·10 Jul 2022An ideal Brayton cycle has a net work output of 150 kJ/kg and backwork ratio of 0.4. if both the turbine and the compressor had an isentropic efficiency of 80%, the net work output of the cycle would be?
misseylaLv10in Mechanical Engineering·10 Jul 2022In an ideal Otto cycle, air is compressed from 1.20 kg/m and 2.2 L to 0.26 L and the net work output of the cycle is 440 kJ/kg. The mean effective pressure for the cycle is?