The chief engineer at a university that is constructing a large number of new student dormitories decides to install a counter flow concentric tube heat exchanger on each of the dormitory shower drains. The thin walled copper drains are of diameter Di = 50 mm. Wastewater from the shower enters the heat exchanger at Th,i= 38°C while fresh water enters the dormitory at Tc,i= 10° The wastewater flows down the vertical wall of the drain in a thin, falling fil , providing hh = 10,000 W/m2. K.If the annular gap is d= 10 mm, the heat exchanger length is L= 1 m, and the water flow rate is m˙ =10 kg/min, determine the heat transfer rate and the outlet temperature of the warmed fresh water.If a helical spring is installed in the annular gap so the fresh water is forced to follow a spiral path from the inlet to the fresh water outlet, resulting in hc = 9050 W/m2.K, determine the heat transfer rate and the outlet temperature of the fresh water.Based on the result for part (b), calculate the daily savings if 15,000 students each take a 10-minute shower per day and the cost of water heating is $0.07/kW.
The chief engineer at a university that is constructing a large number of new student dormitories decides to install a counter flow concentric tube heat exchanger on each of the dormitory shower drains. The thin walled copper drains are of diameter Di = 50 mm. Wastewater from the shower enters the heat exchanger at Th,i= 38°C while fresh water enters the dormitory at Tc,i= 10° The wastewater flows down the vertical wall of the drain in a thin, falling fil , providing hh = 10,000 W/m2. K.If the annular gap is d= 10 mm, the heat exchanger length is L= 1 m, and the water flow rate is m˙ =10 kg/min, determine the heat transfer rate and the outlet temperature of the warmed fresh water.If a helical spring is installed in the annular gap so the fresh water is forced to follow a spiral path from the inlet to the fresh water outlet, resulting in hc = 9050 W/m2.K, determine the heat transfer rate and the outlet temperature of the fresh water.Based on the result for part (b), calculate the daily savings if 15,000 students each take a 10-minute shower per day and the cost of water heating is $0.07/kW.
Precision Machining Technology (MindTap Course List)
2nd Edition
ISBN:9781285444543
Author:Peter J. Hoffman, Eric S. Hopewell, Brian Janes
Publisher:Peter J. Hoffman, Eric S. Hopewell, Brian Janes
Chapter2: Measurement, Materials, And Safety
Section2.1: Introduction To Safety
Problem 14RQ: Class A fire extinguishers use ______ as a media to put out fires.
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Heat Exchangers
Heat exchangers are the types of equipment that are primarily employed to transfer the thermal energy from one fluid to another, provided that one of the fluids should be at a higher thermal energy content than the other fluid.
Heat Exchanger
The heat exchanger is a combination of two words ''Heat'' and ''Exchanger''. It is a mechanical device that is used to exchange heat energy between two fluids.
Question
- The chief engineer at a university that is constructing a large number of new student dormitories decides to install a counter flow concentric tube heat exchanger on each of the dormitory shower drains. The thin walled copper drains are of diameter Di = 50 mm. Wastewater from the shower enters the heat exchanger at Th,i= 38°C while fresh water enters the dormitory at Tc,i= 10° The wastewater flows down the vertical wall of the drain in a thin, falling fil , providing hh = 10,000 W/m2. K.If the annular gap is d= 10 mm, the heat exchanger length is L= 1 m, and the water flow rate is m˙ =10 kg/min, determine the heat transfer rate and the outlet temperature of the warmed fresh water.If a helical spring is installed in the annular gap so the fresh water is forced to follow a spiral path from the inlet to the fresh water outlet, resulting in hc = 9050 W/m2.K, determine the heat transfer rate and the outlet temperature of the fresh water.Based on the result for part (b), calculate the daily savings if 15,000 students each take a 10-minute shower per day and the cost of water heating is $0.07/kW.
Transcribed Image Text:Hot waste water
Warm fresh water
D-
Copper tube
Annulus
Falling film
Cold fresh water
Cool waste water
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