1. An air conditioning unit discharges 5.1 kW of heat to a room at 35°C consuming 1.5 kW of electrical power. (a) Calculate the heat removal rate of the room to be cooled, (b) Calculate the COP of the unit, (c) Calculate the enttopy generation rate of the process, if the room temperature is 23 °C.

1. An air conditioning unit discharges 5.1 kW of heat to a room at 35°C consuming 1.5 kW of electrical power. (a) Calculate the heat removal rate of the room to be cooled, (b) Calculate the COP of the unit, (c) Calculate the enttopy generation rate of the process, if the room temperature is 23 °C.

College Physics

1st Edition

ISBN:9781938168000

Author:Paul Peter Urone, Roger Hinrichs

Publisher:Paul Peter Urone, Roger Hinrichs

Chapter15: Thermodynamics

Section: Chapter Questions

Problem 44PE: An ideal heat pump is being considered for use in heating an environment with a temperature of...

See similar textbooks

Similar questions

(a) What is the rate of heat conduction through the 3.00-cm-thick fur of a large animal having a I .40-m surface area? Assume that the animal's skin temperature is 32.0 , that the air temperature is 5.00 , and that has the same thermal conductivity as air. (b) What food intake will the animal need in one day to replace this heat transfer?
Can improved engineering and materials be employed in heat engines to reduce heat transfer into the environment? Can they eliminate heat transfer into the environment entirely?
Most automobiles have a coolant reservoir to catch radiator fluid than may overflow when 1he engine is hot. A radiator is made of copper and is filled to its 16.0L capacity when at 10.0C. What volume of radiator fluid will overflow when the radiator and fluid reach their 95.0C operating temperature, given that the fluid’s volume coefficient of expansion is =400106/C ? Note that this coefficient is approximate, because most car radiators have operating temperatures of greater than 95.0C.
Under what circumstances would you expect a gas to behave significantly differently than predicted by the ideal gas law?
A person inhales and exhales 2.00 L of 37.0C air, evaporating 4.00102g of water from the lungs and breathing passages with each breath. (a) How much heat transfer occurs due to evaporation in each breath? (b) What is the rate of heat transfer in watts if the person is breathing at a moderate rate of 18.0 breaths per minute? (c) If the inhaled air had a temperature of 20.0C, what is the rate of heat transfer for warming the air? (d) Discuss the total rate of heat transfer as it relates to typical metabolic rates. Will this breathing be a major form of heat transfer for this person?
In 1993, the U.S. government instituted a requirement that all room air conditioners sold in the United States must have an energy efficiency ratio (EER) of 10 or higher. The EER is defined as the ratio of the cooling capacity of the air conditioner, measured in British thermal units per hour, or Btu/h, to its electrical power requirement in watts. (a) Convert the EER of 10.0 to dimensionless form, using the conversion 1 Btu = 1 055 J. (b) What is the appropriate name for this dimensionless quantity? (c) In the 1970s, it was common to find room air conditioners with EERs of 5 or lower. State how the operating costs compare for 10 000-Btu/h air conditioners with EERs of 5.00 and 10.0. Assume each air conditioner operates for 1 500 h during the summer in a city where electricity costs 17.0 per kWh.
One method of converting heat transfer to doing work is for heat transfer into a gas to take place, which expands, dong work on a piston, as shown in the figure below. (a) Is the heat transfer converted directly to work in an isobaric process, or does it go through another form first? Explain your answer. (b) What about in an isothermal process? (c) What about in an adiabatic process (where heat transfer occurred prior to the adiabatic process)?
A heat pump has a coefficient of performance of 3.80 and operates with a power consumption of 7.03 103 W. (a) How much energy does it deliver into a home during 8.00 h of continuous operation? (b) How much energy does it extract from the outside air?
(a) The number of kilocalories in food is determined by calorimetry techniques in which the food is burned and the amount of heat transfer is measured. How many kilocalories per gram ale there in a 5.00-g peanut if the energy from burning it is transferred to 0. 500 kg of water held in a 0.100-kg aluminum cup, causing a 54.9- temperature increase? Assume the process takes place in an ideal calorimeter, in other words a perfectly insulated container. (b) Compare your answer to the following labeling information found on a package of dry roasted peanuts: a sewing of 33 g contains 200 calories. Comment on whether the values are consistent.
(a) Calculate the rate of heat transfer by radiation from a car radiator at 110C into a 50.0C environment, if the radiator has an emissivity of 0.750 and a 1.20m2 surface area. (b) Is this a significant fraction of the heat transfer by an automobile engine? To answer this, assume a horsepower of 200 hp (1.5 kW) and the efficiency of automobile engines as 25%.
What is me Fahrenheit temperature of a person with at 39.0°C fever?
This problem compares the energy output and heat transfer to the environment by two different types of nuclear power stationsone with the normal efficiency of 34.0%, and another with an improved efficiency of 40.0%. Suppose both have the same heat transfer into the engine in one day. 2.501014J. (a) How much more electrical energy is produced by the more efficient power station? (b) How much less heat transfer occurs to the environment by the more efficient power station? (One type of more ef?cient nuclear power station, the gas—cooled reactor, has not been reliable enough to be economically feasible in spite of its greater eficiency.)