Refrigeration and Air Conditioning Technology (MindTap Course List)
8th Edition
ISBN: 9781305578296
Author: John Tomczyk, Eugene Silberstein, Bill Whitman, Bill Johnson
Publisher: Cengage Learning
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Chapter 36, Problem 9RQ
What are higher-efficiency refrigerant blends that can be used as long-term replacements for R-22 in residential and light-commercial air-conditioning applications?
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The LiBr-water absorption cycle shown in the Fig. operates at the following
temperatures: generator, 105 C; condenser, 35 C; evaporator, 5 C; and absorber,
30°C. The flow rate of solution delivered by the pump is 0.4 kg/s.
(a) What are the mass flow rates of solution returning from the generator to the
absorber and of the refrigerant?
(b) What are the rates of heat transfer at each of the components, and the COP?
High-pressure vapor
Solution
105
Generator
Heat
Pump
Monog
Heat
Condenser
Throttling
Expansion
valve
valve
Low-pressure vapor
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Absorber
Evaporator
Heat
A. Using the Steam Tables, determine the amount of cooling water needed by a condenser in kg/sec if wet steam comes into the condenser at P= 610.44mmHG vac and 99.47 % moisture , mass flow rate = 7200 + (10/25) kg/hr. Cooling water enters the condenser at 12 deg C and leaves at 21 deg C. Answer: ___________________
B. Draw the schematic diagram of the condenser and process in the PV and TS diagrams below. Cp H2O = 4.187 KJ/(kg-K):
The catalog for a refrigerant 22, four cylinder, hermetic compressor operating at 29 r/s, a condensing temperature of 40, and an evaporating temperature of -4 shows a refrigerating capacity of 115 kW. At this operating point the motor (whose efficiency is 90%) draws 34.5 kW. The bore of the cylinders is 87 mm and the piston stroke is 70 mm. The performance data are based on 8 of subcooling of the liquid leaving the condenser. Compute (a) the actual volumetric efficiency and (b) the compression efficiency.
Chapter 36 Solutions
Refrigeration and Air Conditioning Technology (MindTap Course List)
Ch. 36 - True or False: Evaporative air-conditioning will...Ch. 36 - What are the advantages of using refrigerated...Ch. 36 - The four major components of an air-conditioning...Ch. 36 - Most compressors are cooled using the ___________.Ch. 36 - What advantage does a thermostatic expansion valve...Ch. 36 - What advantage does a capillary tube have over a...Ch. 36 - The ______expansion device ordinarily must use...Ch. 36 - The most popular refrigerant used in the past for...Ch. 36 - What are higher-efficiency refrigerant blends that...Ch. 36 - What refrigerant blend can be used in retrofit...
Ch. 36 - What types of heat are removed by the evaporator...Ch. 36 - The design boiling point for most evaporator coils...Ch. 36 - What are the three most common types of...Ch. 36 - The large interconnecting line between the indoor...Ch. 36 - The small interconnecting line between the indoor...Ch. 36 - The outside design temperatures in the summerin...Ch. 36 - The dew point temperature tells you how much...
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- Why are there more safety precautions for R-410A than with other popular refrigerants like R-22 and R-404A?arrow_forwardWhy is two-stage compression popular for extra-low-temperature refrigeration systems?arrow_forwardThe most popular refrigerant used in the past for residential air-conditioning is R- ________.arrow_forward
- 1. A. Using the Steam Tables, determine the amount of cooling water needed by a condenser in kg/sec if wet steam comes into the condenser at P= 610.44mmHG vac and 99.47 % moisture, mass flow rate = 7200 + (10/13) kg/hr. Cooling water enters the condenser at 12 deg Cand leaves at 21 deg C. Answer: diagrams below. Cp H20 = 4.187 KJ/kg-K): Schematic diagram of heat exchanger =condenser B. Draw the schematic diagram of the condenser and process in the PV and TS V 2. Use only the MD below to solve this Item; use it by plotting data and process to determine items being asked. Steam enters a turbine at 117.4308 atmgage and 932 deg. F, and expands isentropicaly to 177.17 inches of Hg. For 2 + (10/13 kg/sec of steam, what is (a) the ideal work done (KJ/sec) if AKE = 0 and actual exhaust enthalpy is 2700 KJ/kg. a)Ans: (b)ne =. (c]Determine: ideal steam moisture at exhaust. Ans: (d) Actual steam quality at exhaust Ans: (e) Actual steam temp g) change in entropy during the actual process. at the…arrow_forwardWhy are there more safety precautions for R-410A thanwith other popular refrigerants like R-22 and R-404A?arrow_forwardplease provide full solution for review and comparisonarrow_forward
- Question 4 A VRF cooling unit, having a cooling capacity of 25 kW, have the following COPS: COP100% = 369, COP75% = 5.72, COP50% = 6.65, COP25% = 8.16. Assume that the cooling unit has 13 hours of usage daily, having standby power of 200 W and energy tariffs of 41 cents per kWh. Using NEA's recommended AEC estimation, determine the annual energy cost up to 2 decimal points. Do not include "S" in your answer. Selected Answer: O 5,643.75 Correct Answer 5,584.12 0.01%arrow_forwardPls answer thank you! A re-circulating air bypass system is used to deliver conditioned air to a room at a rate of 5.8 m³/s. Air leaves the air conditioner saturated at 13.5°C dry-bulb. The indoor design dry bulb and wet bulb temperatures are 24.1°C and 18.2°C, respectively. The system bypass factor is 0.34. After the conditioned air is mixed with the bypassed air, what is most nearly the dry-bulb temperature of the air entering the space?arrow_forward1 Photos , 1/1 12:26 PM O 19% I An air cycle refrigeration plant operates with a centrifugal compressor and an air turbine mounted coaxially such that the power output from the turbine contributes to the power required to drive the compressor. The temperature of the air at the compressor inlet is 15'C and the pressure ratio is 2.5. The air during its passage from the compressor to the turbine passes through an intercooler and enters the turbine at 40°C. The cold space temperature is required to be ma intained at 15°C. Taking the isentropic efficiency of both compressor and turbine to be 84% and the mechanical efficiency of the turbine- compressor drive as 90%, calculate the following: Refrigerating effect Mass flow rate per kilowatt of refrigeration capacity Driving power required per kilowatt of refrigeration capacity. i. ii. ii.arrow_forward
- How does a dual-duct warm-air system regulate air temperature?arrow_forwardThe LiBr-water absorption cycle shown in Fig. 17-2 operates at the following temperatures: generator, 100°C; condenser, 55°C; evaporator, 10°C, and absorber, 30°C. The flow rate of solution delivered by the pump is 0.4 kg/s. What is the mass flow rate of refrigerant?arrow_forwardwhat is the mechanism of natural gas Compressors?arrow_forward
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