The ratio of the maximum to minimum pressure.
Answer to Problem 141RP
The ratio of the maximum to minimum pressure is
Explanation of Solution
Determine the COP of a reversible heat pump depends on the temperature limits in the cycle only.
Here, the temperature of higher temperature body is
Determine rate of heat reject by the heat pump minimum.
Here, the power input required to operate the heat pump is
Determine the amount of heat supplied per kg of Carnot heat pump cycle.
Here, the mass flow rate of the working fluid is
Conclusion:
Substitute
Substitute 6.0 for
Substitute
Refer to Table A-4, “Saturated water”, obtain the below properties at the enthalpy of vaporization of
Write the formula of interpolation method of two variables.
Here, the variables denote by x and y are enthalpy of vaporization and temperature.
Show the temperature at
S. No |
enthalpy of vaporization |
Temperature, |
1 | ||
2 | ||
3 |
Calculate final temperature at enthalpy of vaporization of
Substitute
From above calculation the temperature of the working fluid is
Repeat the above Equation (IV) for saturated maximum pressure at
From this cycle maximum absolute temperature in the cycle is 1.2 time the minimum absolute temperature.
Substitute 309.6 K for
Repeat the above Equation (IV) for saturated maximum pressure at
Calculate the ratio of the maximum to minimum pressure.
Here, the minimum pressure is
Substitute 925.3 kPa for
Thus, the ratio of the maximum to minimum pressure is
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Chapter 6 Solutions
THERMODYNAMICS: AN ENGINEERING APPROACH
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