Explanation Given information: The pressure at the entry of the heat exchanger is 150 kPa , temperature at the exit of the heat exchanger is 10 ° C , velocity of the flow at the entry of the heat exchanger is 100 m / s , the amount of heat received in heat exchanger is 120 kJ / kg , the exit pressure is 100 kPa and the velocity of the flow at exit is 200 m / s . Write the expression for the speed of sound. c = k R T ...... (I) Here, the gas constant is R , specific heat ratio is k and the temperature is T . Write the expression for the Mach number. M = v c ...... (II) Here the velocity of the flow is v and the velocity of the sound is c . Write the expression for the heat transferred in the heat exchanger. Q = c v ( T 2 − T 1 ) ...... (III) Here, the temperature at the exit of the heat exchanger is T 2 , the temperature at the inlet of the heat exchanger is T 1 and the specific heat at constant volume is c v . Calculation: Refer to the table A1 "molar mass gas constant and ideal gas specific heat of some substances" to obtain the gas constant for Nitrogen as 0.297 kJ / kg ⋅ K . Refer to the table A1 "molar mass gas constant and ideal gas specific heat of some substances" to obtain the specific heat ratio for nitrogen as 1.4 . Substitute 10 ° C for T , 1.4 for k and 0.297 kJ / kg ⋅ K for R in Equation (I). Refer to the table A1 "molar mass gas constant and ideal gas specific heat of some substances" to obtain the specific heat for constant volume for nitrogen as 0.743 kJ / kg ⋅ K . Substitute 10 ° C for T , 1.4 for k and 0.297 kJ / kg ⋅ K for R in Equation (I). c = ( 1.4 ) ( 0.297 kJ / kg ⋅ K ) ( 10 ° C ) = ( 1.4 ) ( 0.297 kJ / kg ⋅ K ( 1000 J 1 kJ ) ) ( 10 ° C + 273 K ) = 117671.4 J / kg = 343.03 m / s Substitute 343.03 m / s for c and 100 m / s for v in Equation (II) M = 100 m / s 343

Fluid Mechanics: Fundamentals and Applications

4th Edition

ISBN: 9781259696534

Author: Yunus A. Cengel Dr., John M. Cimbala

Publisher: McGraw-Hill Education

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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.

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Chapter 2, Problem 61P

To determine

The Mach at the inlet of the heat exchanger.

The Mach at the outlet of the heat exchanger.

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Chapter 2, Problem 60P

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The Mach at the inlet of the heat exchanger. The Mach at the outlet of the heat exchanger.

Solution Summary: The author explains the Mach at the inlet of the heat exchanger, and its outlet. The gas constant for Nitrogen is 0.297.