An Ocean Thermal Energy Conversion (OTEC) power plant built in Hawaii in 1987 was designed to operate between the temperature limits of 86°F at the ocean surface and 41°F at a depth of 2100 ft. About 13,300 gpm of cold seawater was to be pumped from deep ocean through a 40-in-diameter pipe to serve as the cooling medium or heat sink. If the cooling water experiences a temperature rise of 6°F and the thermal efficiency is 2.5 percent, determine the amount of power generated. Take the density of seawater to be 64 lbm/ft3. Also, take the specific heat of water to be c = 1.0 Btu/lbm-°F. The amount of power generated is kW.

An Ocean Thermal Energy Conversion (OTEC) power plant built in Hawaii in 1987 was designed to operate between the temperature limits of 86°F at the ocean surface and 41°F at a depth of 2100 ft. About 13,300 gpm of cold seawater was to be pumped from deep ocean through a 40-in-diameter pipe to serve as the cooling medium or heat sink. If the cooling water experiences a temperature rise of 6°F and the thermal efficiency is 2.5 percent, determine the amount of power generated. Take the density of seawater to be 64 lbm/ft3. Also, take the specific heat of water to be c = 1.0 Btu/lbm-°F. The amount of power generated is kW.

Refrigeration and Air Conditioning Technology (MindTap Course List)

8th Edition

ISBN:9781305578296

Author:John Tomczyk, Eugene Silberstein, Bill Whitman, Bill Johnson

Publisher:John Tomczyk, Eugene Silberstein, Bill Whitman, Bill Johnson

Chapter44: Geothermal Heat Pumps

Section: Chapter Questions

Problem 1RQ: Geothermal heat pumps, or water-source heat pumps, are classified as either _____loop or _____loop...

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Geothermal heat pumps, or water-source heat pumps, are classified as either _____loop or _____loop systems.
Since Lucas is an engineer familiar with thermodynamics. He decided to create his own heat engine at home to avoid paying for electricity. He created a small, makeshift heat engine for trial. The combustion of his fuel, diesel, reaches a temperature of 750°C, while waste heat is disposed to the atmosphere at 50°C.He, then connected a generator and a heat pump to the heat engine to check the amount of power being produced. Assume that the heat pump will be used to warm his room to 25°C, while the outside temperature is at 5°C. Lucas’ rooms loses 85,000 kJ/hr of heat. And, 25% of the heat engine’s power output goes to the heat pump. How much diesel (in kg) needs to be burned by the heat engine to maintain the temperature in Lucas’ room? Assume carnot heat engine and heat pump. If the natural gas has a heating value of 22,000 BTU/lb. *Round off all answers to four decimal places*
The compressor of a refrigerator using refrigerant R134a draws 1.2 kW. Since the evaporation temperature in the evaporator is -22 °C and the condensation temperature in the condenser is 38 °C; (a) Plot this refrigerator system schematically with its elements and show it on the T-s and P-h diagram of the refrigeration cycle (b) The cooling power of the refrigerator (c) The amount of heat the refrigerator gives to the environment (d) Calculate the ideal and Carnot COP cooling values of this refrigerator.
Since Lucas is an engineer familiar with thermodynamics. He decided to create his own heat engine at home to avoid paying for electricity. He created a small, makeshift heat engine for trial. The combustion of his fuel. diesel, reaches a temperature of 750°C, while waste heat is disposed to the atmosphere at 50°C. He, then connected a generator and a heat pump to the heat engine to check the amount of power being produced. Assume that the heat pump will be used to warm his room to 25°C, while the outside temperature is at 5°C. Lucas' rooms loses 85,000 kJ/hr of heat. And, 25% of the heat engine's power output goes to the heat pump. How much diesel (in kg) needs to be burned by the heat engine to maintain the temperature in Lucas' room? Assume carnot heat engine and heat pump. If the natural gas has a heating value of 22,000 BTU/lb.
Consider a residential heat pump that uses lake water as a heat source in the winter and a heat sink in the summer. The house is to be maintained at a winter temperature of 18oC and a summer temperature of 25oC. To do this efficiently, it is found that the indoor coil temperature should be 50oC in the winter, and 5oC in the summer. The outdoor coil temperature can be assumed to be 5oC during the winter months and 35oC during the summer. Compute for the COPs during (a) winter and (b) summer if it operates as a Carnot cycle heat pump.
Consider mixing some of the ice water with the hot water and vice versa so that the two reservoirs are closer to the same temperature. What do you think will happen to the mechanical/thermodynamic efficiency and ideal Carnot efficiency of the heat engine?
An air-conditioning absorption system has an evaporator capacity of 350 kW with a COP of 0.90 operating at a temperature of 25 C with a condensing temperature of 35 C. The same cooling tower was used to reject the heat from the condenser and the absorber operating 45 C & providing 1 kg/s of water plus lithium bromide solution to the generator. Consider the heat rejection ratio of condenser to evaporator is 1.05, Determine the following: 1. Heat given by the generator & the size of condenser in kW 2. Leaving condenser & evaporator enthalpies & the mass of refrigerant water flowing from the generator to the condenser then to the evaporator & to the absorber (using evaporator heat balance). 3. Weight of lithium bromide in kg/s, concentration in percent & enthalpy from the absorber to the generator in kJ/kg 4. Enthalpy from the generator to condenser in kJ/kg (using condenser heat balance) & concentration in percent & enthalpy from generator to absorber…
A 2 kW, 25 litre storage water heater is used to raise the tem perature of incoming cold water to a desired pre-set end use temperature ranging from 25°C to 75°C Assume that all the electrical energy has gone into heating the water. If the cold water temperature is 15°C and the end use temperature is 50°C. determine the time required to reach the end use temperature after the heater is switched on. The heat capacity cp for water is 4.2 kJ/kgK and density of water is 1000 kg/m3
Steam 90°C 10. A shell-and-tube process heater is to be selected to heat water (Cp = 4190 J/kg-°C) from 20°C to 90°C by steam flowing on the shell side. The heat transfer load of the heater is 600 kW. If the inner diameter of the tubes is 1 cm and the velocity of water is not to exceed 3 m/s, determine how many tubes need to be used in the heat exchanger. 20°C Water
1- A refrigerator is to serve a cooling load of 16 tons. The machine condenser is air cooled and the heat rejection ratio is 1.244. The condenser has an air-side area of 210 m and the overall coefficient of heat transfer based on this area is 37W/m2k. The condenser has a face area of 2.2 m and the face velocity of air is 3 m/s. Density of ambient air is 1.15 kg/m. If the condensing temperature is to be limited to 55°C, what is the maximum allowable ambient temperature ?
An Ocean Thermal Energy Conversion (OTEC) power plant built in Hawaii in 1987 was designed to operate between the temperature limits of 86°F at the ocean surface and 41°F at a depth of 2100 ft. About 13,300 gpm of cold seawater was to be pumped from deep ocean through a 40-in-diameter pipe to serve as the cooling medium or heat sink. If the cooling water experiences a temperature rise of 6°F and the thermal efficiency is 2.5 percent, determine the amount of power generated. Take the density of seawater to be 64 Ibm/ft3. Also, take the specific heat of water to be c = 1.0 Btu/lbm-°F. The amount of power generated is KW.
An air conditioner with refrigerant-134a as the refrigerant is used to keep a large space at 20°C by rejecting the waste heat to the outside air at 37 °C. The room is gaining heat through the walls and the windows at a rate of 125 kJ/min while the heat generated by the computer, TV, and lights amounts to 0.7 kW. Unknown amount of heat is also generated by the people in the room. The condenser and evaporator pressures are 1200 and 500 kPa, respectively. The refrigerant is saturated liguid at the condenser exit and saturated vapor at the compressor inlet. If the refrigerant enters the compressor at a rate of 65 L/min and the isentropic efficiency of the compressor is 70%, determine (a) the temperature of the refrigerant at the compressor exit, (b) the rate of heat generated by the people in the room, (c) the COP of the air conditioner, and (d) the minimum volume flow rate of the refrigerant at the compressor inlet for the same compressor inlet and exit conditions.