The manufacturer of the device claims that it accepts a heat transfer at a rate of QH = 3.0 kW from a low-grade source of geothermal heat at TH = 80ºC and rejects heat at rate QC to the atmosphere at TC = 20ºC. The device operates at steady state and produced work at a rate of W= 2.5 kW. There are no other heat or work transfers from the device.a.) What is the rate at which the device rejects heat to the atmosphere, QC ? b.) Is this device possible? Justify your answer using an entropy balance. Figure illustrates a device advertised on the internet for producing power.TH=80°CW = 2.5 kWQH = 3 kWDevice forproducing powerTc = 20°CQcFigure: Device for producing power.The manufacturer of the device claims that it accepts a heat transfer at a rate of Q = 3.0 kWfrom a low-grade source of geothermal heat at T = 80°C and rejects heat at rate to theatmosphere at Tc = 20°C. The device operates at steady state and produced work at a rate of W= 2.5 kW. There are no other heat or work transfers from the device.a.) What is the rate at which the device rejects heat to the atmosphere, Q?b.) Is this device possible? Justify your answer using an entropy balance.

Answered: Image /qna-images/answer/e9aecf8a-625f-47d9-bf61-7cb1a92fdbb7.jpg

The manufacturer of the device claims that it accepts a heat transfer at a rate of QH = 3.0 kW from a low-grade source of geothermal heat at TH = 80ºC and rejects heat at rate QC to the atmosphere at TC = 20ºC. The device operates at steady state and produced work at a rate of W = 2.5 kW. There are no other heat or work transfers from the device. a.) What is the rate at which the device rejects heat to the atmosphere, QC ? b.) Is this device possible? Justify your answer using an entropy balance.

The manufacturer of the device claims that it accepts a heat transfer at a rate of QH = 3.0 kW from a low-grade source of geothermal heat at TH = 80ºC and rejects heat at rate QC to the atmosphere at TC = 20ºC. The device operates at steady state and produced work at a rate of W = 2.5 kW. There are no other heat or work transfers from the device. a.) What is the rate at which the device rejects heat to the atmosphere, QC ? b.) Is this device possible? Justify your answer using an entropy balance.

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 2.21P

See similar textbooks

Similar questions

A manufacturer in the United States wants to sell a refrigeration system to a customer in Germany. The standard measure of refrigeration capacity used in the United States is the ton (T); a 1 T capacity means that the unit is capable of making about 1 T of ice per day or has a heat removal rate of 12,00 Btu/h. The capacity of the American system is to be guaranteed at 3 T. What is this guarantee in SI units?
Question 2. A household with electric resistance heating plans to switch from resistive heating to a ground source heat pump. Annual heat consumption of the house is 30 000 kWh. Investment cost of the heat pump is 21 000 €. Heat pumps COP is 4.0. How much are the annual savings compared to resistive heating after the change of the heating system (in kWh)? Average price of electricity is assumed to be 12 c/kWh. Round off your answer to one decimal digit and enter it without the unit.
A constant temperature of -125 C must be maintained in a cryogenic experiment, although it gains 120 W due to heat transfer. What is the smallest motor you would need for a heat pump absorbing heat from the container and rejecting heat to the room at 20 C
1) A geothermal facility operates at 1/3 of the Carnot efficiency. If the cold reservoirhas a temperature of 70°C, calculate and plot the efficiency of the facility as afunction of the geothermal fluid temperature from 100°C to 300°C. (remember toconvert to Kelvin!)1b) If a minimum efficiency of 5% is needed for this facility to be economicallyviable, what is the required minimum temperature of the geothermal fluid?
The heat loss from a chicken coop (chicken house) is K(Tnside - Totside) during the winter, where K is 1.5 kW/K. The chicken coop temperature can vary between 15 °C and 25 °C without harming egg production. A heat pump with a coefficient of performance of 40% of that of a reversible heat pump is used to heat the chicken coop. What are the minimum power requirements if the outside temperature is -5 °C? .
A 3.0-inch wall of fire brick, k = 8.0 Btu/ (ft)(hr) (CF/ in) has one surface at 335°F, the other at 80°F. Find the heat conducted through an area of 1.4 ft? in one day.
Example 1.3 160 MW. Its annual load factor is 0.6. The coal consumption is 1 kg per kWh of energy A thermal power plant of 210 MW capacity has the maximum load of generated and the cost of coal is Rs 450.00 per tonne. Calculate (a) the annual revenue earned if energy is sold at Re 1 per kWh and (b) the capacity factor of the plant.
Problem An electric heater is to heat 18 kg of oil per min. from 24.5 °C to 185.5 °C. Specific heat of oil is 2.018 KJ/kg- °C.Calculate the power consumed by the heater. Ans. Problem The overall efficiency of an electric system, coal pile to lights a lamp is What fraction of a kg of coal containing 1350 W lamp for 45 minutes? 97.4694 Kw 18 %. 10250 KJ/kg must be consumed to light a Ans. 1.976 KJ
3.15 The heating rate that a heat pump delivers to a living space of tempera- ture 20°C is 5 kW. The coefficient of performance of the heat pump is COP = 2. The temperature of the ambient is 0°C. (a) What is the electrical power required by the heat pump? (b) What is the rate at which the heat pump draws heat from the ambient? (c) What is the highest COP value that the heat pump may attain? (d) Is the operation of this heat pump violating the second law of thermodynamics?
Q1. Find the heat flow rate through the composite wall as shown in Fig. below. Assume one dimensional flow & the area is variable for each layer. Where: kA = 152 W/m°C, kB = 31 W/m°C, kC = 68 W/m°C and → 60°C :3 cm kD = 53 W/m°C. B 17 cm 400°C A 10 cm 5 cm 8 cm cm
2) The energy consumed by a shower for 30 days is 22kwh. It is known that the resistance of the showerhead is 20 ohms and that its nominal current is 15A. So, what is the time in minutes that the shower was turned on during this period?
A liquid reactant solution is pumped through a pre-heater before entering a reaction vessel. The solution enters the pre-heater at 25 °C and must enter the reactor at 45 °C. The flow of the reactant solution is 1500 mL per minute. The density of the reactant solution is 0.91 g-cm3 and the heat capacity is 1.75 Jg1.K1. ASsume there is no heat loss in the pre-heater or between the pre-heater and the reactor. a. Draw a schematic of the pre-heater, detailing all mass and energy flows. b. Clearly define a system boundary. c. Write the general energy balance, and a simplified energy balance stating all assumptions that apply to this problem. d. What is the minimum power rating required for the pre-heater?