A counter-flow heat exchanger is used to cool water from 60°C to 20°C. The water flows at 0.2 m/s through the inner tube and the cooling fluid flows in the enclosure. The inner tube is 6-cm in diameter and 15-m in length. It is thin and made of copper. The flow rate of the cooling fluid is 1.2 kg/s and convection coefficient is 360 W/m².°c. The specific heat of the cooling fluid is 1600 J/kg. °C. The surface temperature of the inner tube can be approximated as almost isothermal. (a) What is the mass flow rate of water? 0.56 kg/s (b) What is the effectiveness of this heat exchanger? 0.285

A counter-flow heat exchanger is used to cool water from 60°C to 20°C. The water flows at 0.2 m/s through the inner tube and the cooling fluid flows in the enclosure. The inner tube is 6-cm in diameter and 15-m in length. It is thin and made of copper. The flow rate of the cooling fluid is 1.2 kg/s and convection coefficient is 360 W/m².°c. The specific heat of the cooling fluid is 1600 J/kg. °C. The surface temperature of the inner tube can be approximated as almost isothermal. (a) What is the mass flow rate of water? 0.56 kg/s (b) What is the effectiveness of this heat exchanger? 0.285

Elements Of Electromagnetics

7th Edition

ISBN:9780190698614

Author:Sadiku, Matthew N. O.

Publisher:Sadiku, Matthew N. O.

ChapterMA: Math Assessment

Section: Chapter Questions

Problem 1.1MA

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To cool the lubricating oil, a concentric counter-flow heat exchanger is utilized, with the water flowing via an internal pipe with an internal diameter of 0.02 m and a flow rate of 0.18 kg/s. The intake and output oil temperatures are 95ºC and 65ºC, respectively, as the oil runs through the outer annulus (0.04 m) at a flow rate of 0.12 kg/s. The water enters the heat exchanger at a temperature of 30ºC. Stating all the necessary assumptions, (a) determine required length of the pipe. (b) Considering the effect of fouling during operation through time and the heat transfer resistance would be affected, discuss the design and operation considerations to minimize the fouling problem on the opertion of the heat exchanger during design and operation stages. Consider average value of Engine oil property: Cp=2131 J/kgoC; μ=0.0325 Ns/m2; K=0.138 W/moC Consider average value of water properties: Cp=4174 J/kgoC; μ=725x 10-6 Ns/m2; K=0.138 W/moC; Pr=4.85
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