)aA double pipe heat exchanger is constructed of a copper (k=380Wm.K) inner tube of internal diameter D1=1.2cm and external diameter D0=1.6cm and an outer tube diameter 3.0cm.The convection heat transfer coefficient is reported to be hi=700W/m2.K on the inner surface of the tube and h0 =1400W/m2.K on its outer surface.For a fouling factor Rf,I=0.0005m2.K/W on the tube side and Rf,o=0.0002m2.K/W on the shell side, determine (I) the thermal resistance of the heat exchanger per unit length.(ii) the overall heat transfer coefficients Ui and U0 base on the inner and outer surface area of the tube, respectively. (b)Classify heat exchangers according to the flow type and explain the characteristics of each type. (c)How does the presence of baffles affect the heat transfer and the pumping power requirements? Explain (d) Consider a hot baked potato.Will the potato cool faster or slower when we blow the warm air coming from our lungs on it instead of letting it cool naturally in the cooler air in the room? Explain. (e)In which mode heat transfer is convection heat transfer coefficient usually higher, natural convec
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.
(1)aA double pipe heat exchanger is constructed of a copper (k=380Wm.K) inner tube of internal diameter D1=1.2cm and external diameter D0=1.6cm and an outer tube diameter 3.0cm.The convection heat transfer coefficient is reported to be hi=700W/m2.K on the inner surface of the tube and h0 =1400W/m2.K on its outer surface.For a fouling factor Rf,I=0.0005m2.K/W on the tube side and Rf,o=0.0002m2.K/W on the shell side, determine (I) the thermal resistance of the heat exchanger per unit length.(ii) the overall heat transfer coefficients Ui and U0 base on the inner and outer surface area of the tube, respectively.
(b)Classify heat exchangers according to the flow type and explain the characteristics of each type.
(c)How does the presence of baffles affect the heat transfer and the pumping power requirements? Explain
(d) Consider a hot baked potato.Will the potato cool faster or slower when we blow the warm air coming from our lungs on it instead of letting it cool naturally in the cooler air in the room? Explain.
(e)In which mode heat transfer is convection heat transfer coefficient usually higher, natural convection or force convection.
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