Explanation Consider the system is in steady state. Hence, the inlet and exit mass flow rates are equal. The mass flow rate of air ( m ˙ a ) is as follows. m ˙ 1 = m ˙ 2 = m ˙ a The mass flow rate of water ( m ˙ w ) is as follows. m ˙ 3 = m ˙ 4 = m ˙ w The flow work of air is expressed as follows. w flow,a = P 2 v 2 − P 1 v 1 (I) Here, the pressure is P , the specific volume is v and the subscripts 1 and 2 indicates the initial and final states of air. Write the ideal gas relation. P v = R T Here, the gas constant is R and the temperature is T . Since, the air is an ideal gas. Rewrite the Equation (I) with reference to the ideal gas relation as follows. w flow,a = R T 2 − R T 1 = R ( T 2 − T 1 ) (II) The flow work of water is expressed as follows. w flow,w = P 4 v 4 − P 3 v 3 (III) Write the formula total flow power required. W ˙ flow = m ˙ a w flow,a + m ˙ w w flow,w (IV) Write the formula for mass flow rate of air. m ˙ a = V ˙ P 1 R T 1 (V) Here, the volumetric flow rate of air is V ˙ , the pressure is P , the gas constant of air is R and the temperature is T ; the suffix 1 indicates the inlet condition of air. For water: At inlet: The water is at the state of saturated water. Refer Table A-4E, “Saturated water–Temperature table”. Obtain the inlet specific volume ( v 3 ) corresponding to the temperature of 50 °F . v f @ 50 ° F = v 3 = 0.01602 ft 3 /lbm At exit: Still, the water is at the state of saturated water. Refer Table A-4E, “Saturated water–Temperature table”. Obtain the outlet specific volume ( v 4 ) corresponding to the temperature of 90 °F . v f @ 90 ° F = v 4 = 0.01610 ft 3 /lbm Refer Table A-1E, “Molar mass, gas constant, and critical-point properties”. The gas constant ( R ) of air, in Btu/lbm ⋅ R is 0.06855 Btu/lbm ⋅ R . The gas constant ( R ) of air, in psia ⋅ ft 3 /lbm ⋅ R is 0.3704 psia ⋅ ft 3 /lbm ⋅ R . Conclusion: Substitute 0.06855 Btu/lbm ⋅ R for R , 100 ° F for T 2 , and 200 °F for T 1 in Equation (II). w flow,a = 0.06855 Btu/lbm ⋅ R ( 100 °F − 200 ° F ) = 0.06855 Btu/lbm ⋅ R [ ( 100 + 460 ) R − ( 200 + 460 ) R ] = 0.06855 Btu/lbm ⋅ R ( − 200 R ) = − 6

9th Edition

ISBN: 9781266084584

Author: CENGEL

Publisher: MCG

See similar textbooks

Concept explainers

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.

Videos

Question

Chapter 5.5, Problem 149RP

To determine

The total flow power, in hp, required and the flow work, in Btu/lbm for both air and water streams.

Expert Solution & Answer

Want to see the full answer?

Check out a sample textbook solution

See solution

Chapter 5.5, Problem 148RP

Chapter 5.5, Problem 150RP

Students have asked these similar questions

In a power plant steam, steam is continuously extracted from the turbine and in a heat exchanger there is a condensation of the extracted steam. The energy released during condensation of steam is used to operate a heat engine. A heat engine receives thermal energy at a rate of 1250 kJ/min from condensing steam and rejects waste heat to a lake at 20°C at a rate of 800 kJ/min. Determine the lowest possible condensing steam temperature.

A refrigeration system uses a water-cooled condenser for rejecting the waste heat. The system absorbs heat from a space at 25°F at a rate of 21,000 Btu/h. Water enters the condenser at 65°F at a rate of 1.45 lbm/s. The COP of the system is estimated to be 1.9. Determine the temperature of the water at the exit of the condenser in °F.

Refrigerant-134a enters the condenser of a residential heat pump at 800 kPa and 358C at a rate of 0.018 kg/s and leaves at 800 kPa as a saturated liquid. If the compressor consumes 1.2 kW of power, determine (a) the COP of the heat pump and (b) the rate of heat absorption from the outside air

Chapter 5 Solutions

THERMODYNAMICS: ENG APPROACH LOOSELEAF

Ch. 5.5 - Name four physical quantities that are conserved...Ch. 5.5 - Define mass and volume flow rates. How are they...Ch. 5.5 - Does the amount of mass entering a control volume...Ch. 5.5 - Consider a device with one inlet and one outlet....Ch. 5.5 - The ventilating fan of the bathroom of a building...Ch. 5.5 - Air enters a 16-cm-diameter pipe steadily at 200...Ch. 5.5 - A steam pipe is to transport 200 lbm/s of steam at...Ch. 5.5 - A garden hose attached with a nozzle is used to...Ch. 5.5 - A steady-flow compressor is used to compress...Ch. 5.5 - Air enters the 1-m2 inlet of an aircraft engine at...

Knowledge Booster

Learn more about

Need a deep-dive on the concept behind this application? Look no further. Learn more about this topic, mechanical-engineering and related others by exploring similar questions and additional content below.

The total flow power, in hp , required and the flow work, in Btu/lbm for both air and water streams.

Solution Summary: The author explains the flow power and flow work required for both air and water streams. The mass flow rate of air is as follows.

Concept explainers

Videos

The total flow power, in hp, required and the flow work, in Btu/lbm for both air and water streams.

Want to see the full answer?

Chapter 5 Solutions