H6. An air conditioner in an upper-floor apartment unit is turned on during a hot summer afternoon. If heat can be removed from the interior at a rate of 1.5 kW, estimate the time required to cool the air inside the apartment to its final temperature. Your estimate should create any needed input data and should incorporate factors like the size of the apartment and the behavior of air

H6. An air conditioner in an upper-floor apartment unit is turned on during a hot summer afternoon. If heat can be removed from the interior at a rate of 1.5 kW, estimate the time required to cool the air inside the apartment to its final temperature. Your estimate should create any needed input data and should incorporate factors like the size of the apartment and the behavior of air

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.

Chapter8: Natural Convection

Section: Chapter Questions

Problem 8.46P

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1. In an analysis, a heat engine based on the Carnot cycle operating between 1000 0C and 300 0C. The heat rejected from this engine to the sink was at a rate of 800 kJ/min. Determine the thermal efficiency (in %) and power output (in kW) of the engin 2.You found out that the power output of your dream car is the same as the sum of each digits of your student number (in kW) with a percentage thermal efficiency the same as the first four digit of your student number divided by 100. The calorific value of the fuel available has a calorific value of 40 000 kJ/kg. Assuming a constant power output from the car, calculate the heat transfer rate (in kW) and the fuel consumption rate (in kg/h)
An electric home stove with 3 burners and microwave is used in preparing a meal asfollows. Burner 1: 20 minutes Burner 2: 40 minutes Burner 3: 15 minutes . Microwave: 30minutes. If each burner is rated at 1.2 kW and the oven at 1.8 kW, and electricity costs 1000(IQ =Iraqi Dinar) per k Wh, calculate the cost of electricity used in preparing the meal?
A student buys a 5000 Btu window air conditioner for his apartment bedroom. He monitors it for one hour on a hot day and determines that it operates approximately 60 percent of the time (duty cycle = 60 percent) to keep the room at nearly constant temperature. (a) Showing all your work and using unity conversion ratios, calculate the rate of heat transfer into the bedroom through the walls, windows, etc. in units of Btu/h and in units of kW. (b) If the energy efficiency ratio (EER) of the air conditioner is 9.0 and electricity costs 7.5 cents per kilowatt-hr, calculate how much it costs (in cents) for him to run the air conditioner for one hour.
. a. A group of engineering students designs an electric heater with a power rating of 15 kW. If 10 kg of ice at 200 K is placed in the heater, how many minutes will it take to change ice to steam at 400 K. Assume 100% efficient.
With a 1 kW pump, the energy leakage per unit time is 0.6 kW for a 1 ℃ temperature difference between a house to be heated and the outside environment. Coefficient of performance of the heat pump used to keep this house at a constant temperature of 20 ℃; If it is up to the theoretical heat pump performance coefficient; What is the minimum outdoor temperature ℃ for this heat pump to meet its needs and be used?
Tec A solar hot-water-heating system consists of a hot-water tank and a solar panel. The tank is well insulated and has a time constant of 64 hr. The solar panel generates 1900 Btu/hr during the day, and the tank has a heat capacity of 3°F per thousand Btu. If the water in the tank is initially 112 F and the room ewd temperature outside the tank is 80°F, what will be the temperature in the tank after 11 hr of sunlight? After 11 hr of sunlight, the temperature in the tank will be about | PF. (Round to the nearest tenth as needed.) nts estl
A certain refrigerator has a COP of 5.00. When the refrigerator is running, its power input is 500 W. A sample of water of mass 500 g and temperature 20.0°C is placed in the freezer compartment. Assume all other parts of the refrigerator stay at the same temperature and there is no leakage of energy from the exterior, so the operation of the refrigerator results only in energy being extracted from the water. -->Compare the cost to make 44 kg of ice using two different refrigerators; one has a COP of 5.00 and the other has a COP of 6.00. Electricity costs $0.10 per kWh. Using the same assumptions given in the example, find the cost difference (in dollars) between the refrigerators to freeze the water.
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…
b) Refrigerators are systems that are used to remove heat from a cooled space then reject heat to a space of higher temperature. Consider a refrigerator operating at normal conditions, removing heat from a cool space at a rate of 150 kJ/min to ensure the refrigerated space is kept at -5 °C. If the surrounding air is at 27 °C and assuming that the refrigerator is operating as a Carnot cycle, determine: 1) The rate of heat being rejected to the surrounding in kJ/min The coefficient of performance of this refrigeration process 11) 111) The minimum required power on this process (give your answer in kW)
1. A geothermal heat pump with a COP of 1.3 provides 48000 BTU/hr of heat to a building. Assuming an electrical power rate of $0.20/kWh. answer the following questions for this system: a. What would be the monthly cost to provide heat at a rate of 48000 BTU/hr if the heat was delivered by a simple electrical resistance heater? b. How much heat is drawn from the ground by the heat pump in that month, in kWh? c. What is the savings per month enjoyed by operating this heat pump for a month vs. a simple electrical resistance heater?
A geothermal heat pump with a coefficient of performance of 1.3 supplies a building with 48000 BTU/hr of heat. Assuming a $0.20/kWh electricity rate. Provide responses to the following questions about this system: a. How much would it cost per month to supply heat at a rate of 48000 BTU/hr using a basic electrical resistance heater? b. In that month, how much heat is extracted from the earth by the heat pump, in kWh? c. What is the monthly savings associated with using this heat pump vs a basic electrical resistive heater?
THERMODYNAMICS 1. Calculate the amount of energy required in BTU to heat the air in a house 30 by 50 by 40 ft from 10 to 70°F at constant pressure. 2. Brine enters a cooler at the rate of 50 m3/hr at 15°C and leaves at 1°C. Specific heat and specific gravity of brine are 1.07 kJ/kg–K and 1.1 respectively. Calculate the heat transferred in kW. 3. How many BTU/min is required to produce 10 metric tons of ice per day at -10°C from raw water at 22°C? The latent heat of fusion of ice is 335 kJ/kg.