An air conditioning system is operating in an ambient of 45°C. The room temperature is maintained at 25°C. Determine the power consumption of the system per ton of refrigeration if it is, (a) air-cooled as in a window-type air conditioner; (b) water-cooled as in a central air conditioning plant. The cooling water from cooling tower is available at 30°C. Assume suitable operating temperatures. Actual COP of the system is only 50% of the COP of the reversible cycle.

An air conditioning system is operating in an ambient of 45°C. The room temperature is maintained at 25°C. Determine the power consumption of the system per ton of refrigeration if it is, (a) air-cooled as in a window-type air conditioner; (b) water-cooled as in a central air conditioning plant. The cooling water from cooling tower is available at 30°C. Assume suitable operating temperatures. Actual COP of the system is only 50% of the COP of the reversible cycle.

Principles of Heat Transfer (Activate Learning with these NEW titles from Engineering!)

8th Edition

ISBN:9781305387102

Author:Kreith, Frank; Manglik, Raj M.

Publisher:Kreith, Frank; Manglik, Raj M.

Chapter2: Steady Heat Conduction

Section: Chapter Questions

Problem 2.63P

See similar textbooks

Similar questions

3.) When a gas surrounded by air is compressed or expands adiabatically, its temperature rises or decreased even though there is no heat input or dissipated to the gas. Where does the energy come from to raise or lower the temperature?
You, a process design engineer, are tasked to build a powerplant with a net output of 1 MW. First, in an industrial boiler, coal is burned to heat and pressurize 1.6 kg/s of water pumped from an underground reservoir (25 oC, 1 atm) to High Pressure Steam (44 atm, 450 oC). The industrial boiler is insulated, but due to the high temperatures and the nature of the process there are inevitably heat losses. As such, the total heat losses of the whole system is around 20% of the heat from the coal. The High-Pressure Steam, moving at a linear velocity of 70 m/s, is then used to drive a turbine. The low pressure steam from the turbine is used to preheat the boiling water and then released to the atmosphere as saturated steam (100oC and1atm) at a velocity of 10 m/s via an exhaust 10 m above the turbine inlet. How much heat is needed for the powerplant? Use the following values of enthalpy: Water from reservoir 25oC; 1atm H=104.93 kJ/kg High Pressure Steam 450oC; 44atm H=3324.63 kJ/kg Low…
A heat pump used for heating shown is essentially an air conditioner installed backward. It extracts energy from colder air outside and deposits it in a warmer room. Suppose the ratio of the actual energy entering the room to the work done by the device’s motor is 10.0% of the theoretical maximum ratio. Determine the energy entering the room per joule of work done by the motor given that the inside temperature is 20.0°C and the outside temperature is -5.00°C.
An air conditioning unit works by taking heat out of a room. As the refrigerant gas expands in the cooling coils, it absorbs heat from the circulating air in the room. This heat is then released as the refrigerant is compressed by the part of the unit that is directed out of the room. The unit serves like a heat pump for the room. Since a refrigerator works in a similar manner, can t also be used to maintain a cool temperature inside a room? Justify your answer.
While 50 kJ of heat is input to the closed system, a 5 kN.m work input occurs with a mixer placed in the same system. The initial internal energy of the system is 70 If kJ is what is the final internal energy?
1) Water vapor with a flow rate of 20000 kg / h enters the condenser of a power plant at a pressure of 20 kPa and a dryness degree of 95 percent. In the condenser, there is heat transfer to the river water flowing through the pipes. The temperature rise of the river water is limited to 10'C to prevent thermal pollution. Since the state of the water at the condenser outlet is saturated liquid at 20 kPa pressure, what should be the flow rate of the cooling water.
Goal Solve for the efficiency of a heat engine using a five-step process the includes:1. Making a state table.2. Making a process table.3. Calculating the totals for Work, Heat, and Internal-Energy-Change.4. Identifying the heat input (hot reservoir) and output (cold reservoir).5. Calculating the efficiency of the engine.Problem Shown in the figure to the right is a cyclic process undergone by a heat engine. Your heat engine shall use 7.0 moles of nitrogen gas (diatomic). During the process a->b, the pressure rises by a factor of 2.0. solution- (1) Fill in the State Table (all pressures in Pascals, all volumes in cubic meters, all temperatures in K). Pressure Volume Temperature a b c (2) Fill in the Process Table (all entries in Joules). Work Heat dU a->b b->c c->a (3) Find the Totals: Work = J Heat = J dU = J (4) Find the heat input (from "hot reservoir") and the heat output (to…
Suppose you have two kettles – a plug-in electric kettle and a stovetop kettle. The electric kettle uses electricity from a natural gas fired powerplant, while you boil water in your stovetop kettle on a natural gas burner. a) Based on the following information, which of these kettles demonstrates a higher energy efficiency (i.e., which is more efficient at using energy from fuel to heat water)? Please calculate the efficiencies of each kettle and express answers as percentages. -The natural gas power plant converts chemical energy of the natural gas to electricalenergy with 58% efficiency. -High-voltage power lines from the power plant to your house convey electricity with92% efficiency. -The electric kettle converts electrical energy to thermal energy in the water with 85%efficiency (the other 15% heats up the kettle itself). -The stove burner converts chemical energy of natural gas to thermal energy with 98%efficiency (the other 2% is light). -The stovetop kettle transfers 35% of…
The figure below shows a schematic of a dual-duct system For design purposes, suppose the zones shown are two of five zones, each having identical operating design conditions. The only exhaust is the main system exhaust. The zones are to held at 75 °F db / 50% RH when the total heat gain of each one is 200,000 BTUH and the sensible heat ratio is 0.6. Outside air (OA) is 95 °F db / 40% RH and the system is designed to operate with a mass flow rate of dry air that contains 25% OA & 75% RA (return air). The hot deck provides sensible heating only, and the air exits the heating coil at 105 °F db. The cold deck is designed such that air exits the cooling coil at 50 °F db / 90 % RH. Take the pressure to be one standard atmosphere. a. Accurately sketch and label the state points on an electronic psych chart (in particular make sure that the coil is represented as a collie on the TRANE pscyh chart software you can input a coil process) b. Compute the mass flow rate (lbma/hr) through…
Unreasonable Results - A slightly deranged Arctic inventor surrounded by ice thinks it would be much less mechanically complex to cool a car engine by melting ice on it than by having a water-cooled system with a radiator, water pump, antifreeze, and so on. (a) If 80% of the energy in 1.00 gal of gasoline is converted into “waste heat” in a car engine, how many kilograms of 0C ice could it melt? (b) Is this a reasonable amount of ice to carry around to cool the engine for 1.00 gal of gasoline consumption? (c) What premises or assumptions are unreasonable?
Hello Sir,Good Morning.I have a question in my homework related thermodynamics lesson. The following below is my question. Please advice. Thank you. Regards,Irfan An air conditioning system is used to keep the house at 65°F when the outside temperature is 85°F. The house gets heat through the walls and windows at a rate of 810 Btu/min, and the rate of heat generation inside the house from occupants, lights, and equipment is 120 Btu/min. Determine the minimum power input required for this air conditioning system.
A pressure cooker operates by cooking food at a higher pressure and temperature than is possible at atmospheric conditions. Steam is contained in the sealed pot, with a small vent hole in the middle of the cover, allowing steam to escape. The pressure is regulated by covering the vent hole with a small weight, which is displaced slightly by the escaping steam. Atmospheric pressure is 1 bar, the vent hole area is 7mm2, and the pressure inside should be 2.75 bar. What is the mass in kg of the small weight?