Explanation Sketch the schematic layout of the two-stage compression refrigeration system as in Figure (1). Sketch the T − s diagram of the two-stage compression refrigeration as in Figure (2). Write the relation between the specific enthalpies at the inlet and exit of throttling. h i = h e (I) Here, specific enthalpy of the refrigerant at the inlet of throttling is h i and specific enthalpy of the refrigerant at the exit of throttling is h e . Write the energy balance equation for the separator. m ˙ 6 ( h 8 − h 5 ) = m ˙ 2 ( h 1 − h 4 ) m ˙ 6 = m ˙ 2 h 1 − h 4 h 8 − h 5 (II) Here, mass flow rate of the refrigerant at the end of high pressure compressor is m ˙ 2 , mass flow rate at the inlet of evaporator is m ˙ 6 , specific enthalpy of refrigerant at the compressor inlet of high pressure cycle is h 1 , specific enthalpy at the exit of expansion valve at high pressure cycle is h 4 , specific enthalpy at the exit of compressor at the low pressure cycle is h 8 , and the specific enthalpy at the inlet of expansion valve at the low pressure cycle is h 5 . Write the expression to calculate the rate of cooling produced ( Q ˙ L ) by the two-stage compression refrigeration. Q ˙ L = m ˙ 6 ( h 7 − h 6 ) (III) Here, specific enthalpy at the inlet of low pressure compressor is h 7 and the specific enthalpy at the inlet evaporator is h 6 . Write the expression to calculate the total power input to the compressor ( W ˙ in ) of the system. W ˙ in = m ˙ 6 ( h 8 − h 7 ) + m ˙ 2 ( h 2 − h 1 ) (IV) Here, specific enthalpy at the exit of high pressure compressor is h 2 . Conclusion: From the Table A-11 of “Saturated refrigerant R-134a: Temperature”, obtain the properties of refrigerant at high pressure compressor inlet temperature ( T 1 ) of 8.9 ° C as follows: h 1 = h g = 255.60 kJ / kg s 1 = s g = 0.92711 kJ / kg ⋅ K From the Table A-13 of “Superheated refrigerant R-134a”, obtain the specific enthalpy of high pressure compression exit at pressure ( P 2 ) of 1400 kPa and specific entropy of 0.92711 kJ / kg ⋅ K as 281.56 kJ / kg . From the Table A-12 of “Saturated refrigerant R-134a: Pressure”, obtain the properties of refrigerant at high pressure cycle throttle inlet pressure of 1400 kPa as follows: h 3 = h f = 127.25 kJ / kg Substitute 127.25 kJ / kg for h 3 in Equation (I). h 4 = 127.25 kJ / kg From the Table A-12 of “Saturated refrigerant R-134a: Pressure”, obtain the properties of refrigerant at low pressure cycle throttle inlet temperature of 8.9 ° C as follows: P 5 = P sat = 400 kPa h 5 = h f = 63.91 kJ / kg Here, pressure of refrigerant at the separator is P 5 . Substitute 63.91 kJ / kg for h 5 in Equation (I). h 6 = 63.91 kJ / kg From the Table A-11 of “Saturated refrigerant R-134a: Temperature”, obtain the properties of refrigerant at low pressure compressor inlet temperature ( T 7 ) of − 32 ° C as follows: h 7 = h g = 230

8th Edition

ISBN: 9780073398174

Author: Yunus A. Cengel Dr., Michael A. Boles

Publisher: McGraw-Hill Education

See similar textbooks

Videos

Question

Chapter 11.10, Problem 116RP

To determine

The rate of cooling produced by the two stage compression system.

The total power input required to the compressor.

Expert Solution & Answer

Want to see the full answer?

Check out a sample textbook solution

See solution

Chapter 11.10, Problem 114RP

Chapter 11.10, Problem 117RP

Students have asked these similar questions

What is the reason for this composition?

Homework: ANOVA Table for followed design B AB Dr -1 -1 1 (15.18,12) 1 -1 -1 (45.48.51) -1 1 -1 (25,28,19) 1 1 (75.75,81)

S B Pin 6 mm G

Chapter 11 Solutions

Thermodynamics: An Engineering Approach

Ch. 11.10 - Why is the reversed Carnot cycle executed within...Ch. 11.10 - Why do we study the reversed Carnot cycle even...Ch. 11.10 - 11–3 A steady-flow Carnot refrigeration cycle uses...Ch. 11.10 - Does the ideal vapor-compression refrigeration...Ch. 11.10 - Why is the throttling valve not replaced by an...Ch. 11.10 - It is proposed to use water instead of...Ch. 11.10 - In a refrigeration system, would you recommend...Ch. 11.10 - Does the area enclosed by the cycle on a T-s...Ch. 11.10 - Consider two vapor-compression refrigeration...Ch. 11.10 - The COP of vapor-compression refrigeration cycles...

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 rate of cooling produced by the two stage compression system. The total power input required to the compressor.

Videos

The rate of cooling produced by the two stage compression system. The total power input required to the compressor.

Want to see the full answer?

Chapter 11 Solutions

The rate of cooling produced by the two stage compression system.

The total power input required to the compressor.