An air conditioning system is designed under the following conditions Ourdoor conditions; 30°C dbt, 75% RH Required indoor conditions; 22°C dbt, 70% RH Amount of free air circulated; 3.33 m/sec Coil dew point temperature; 14°C Therequired condition is achieved first by cooling and dehumi dification and then by Teating. Estimate (1) Capacity of cooling coil intons and its efficiency. ii) Capacity of heating coil in kW. ii) Amount of water vapour removed kg/sec,

An air conditioning system is designed under the following conditions Ourdoor conditions; 30°C dbt, 75% RH Required indoor conditions; 22°C dbt, 70% RH Amount of free air circulated; 3.33 m/sec Coil dew point temperature; 14°C Therequired condition is achieved first by cooling and dehumi dification and then by Teating. Estimate (1) Capacity of cooling coil intons and its efficiency. ii) Capacity of heating coil in kW. ii) Amount of water vapour removed kg/sec,

Refrigeration and Air Conditioning Technology (MindTap Course List)

8th Edition

ISBN:9781305578296

Author:John Tomczyk, Eugene Silberstein, Bill Whitman, Bill Johnson

Publisher:John Tomczyk, Eugene Silberstein, Bill Whitman, Bill Johnson

Chapter36: Refrigeration Applied To Air-conditioning

Section: Chapter Questions

Problem 2RQ: What are the advantages of using refrigerated air-conditioning rather than evaporative conditioning?

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What are the advantages of using refrigerated air-conditioning rather than evaporative conditioning?
A R22 refrigeration system is used to operate between 45degC and -30degC. The total cooling capacity is 350 kW. a. What is the ideal COP of the system? b. What is the heat rejected by the system? c. What is the total power consumed by the system? There are several steps made to improve the performance of the system. What happens to the COP, heat rejected and power consumed by the system when: d. For the same evaporator and condenser pressure, the temperature at the entrance of the compressor is -20degC, and the inlet to the expansion valve is subcooled by 5degC. Due to the wide temperature gap, it is decided to use a two-stage refrigeration system using flash gas removal and optimal intercooling operation in a flash chamber. What happens to the COP, heat rejected and power consumed by the system when: e. Having a low pressure and high-pressure compression. f. Two evaporators and two compressors, with the lower temperature evaporator having a cooling capacity of 225 kW. Notes: The…
I. ESSAY/ ENUMERATION 1. GIVE ATLEAST 5 ADVANTAGES AND 5 DISADVANTAGES OF INORGANIC REFRIGERANTS. 2. HOW DOES A REFRIGERANT WORKS IN A REFRIGERATION SYSTEM? 3. DIFFERENTIATE POSITIVE AZEOTTROPES AND NEGATIVE AZEOTROPES IN TERMS OF THEIR APPLICATION IN REFRIGERATION SYSTEMS. 4. THE FOUR MAIN COMPONENTS OF A REFRIGERATION SYSTEM ARE COMPRESSOR, CONDENSER, EVAPORATOR AND AN EXPANSION VALVE. EXPLAIN BRIFLY THE FUNCTION OF EACH COMPONENT AND THE FLOW OF THE CYCLE.
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9.2 In a 112 TR R 22 flooded chiller, the water inlet temperature is 11.67°C. The mass flow rate of water to be chilled is 18.93 kg/s. The evaporating tempera- ture of the refrigerant is 2.8°C. The copper tubes used are 1.27 cm OD and 1.12 cm ID. There are two parallel circuits and eight passes for water. The refrigerant-side heat-transfer coefficient is given by Rohsenow's correlation. Calculate the overall heat-transfer surface area of the chiller.
Problem 3 For the system to the right, why would we want to heat the hot water heater using the HVAC system, rather than more traditional methods (such as burning natural gas)? Home inside nir temp: 20°C hot wnter henter - 10 liters imax temp: 50'C) Subrooler (autside air temmp: 32°C) R14a refrigerant PJ P2 sat. Hquid Qhot-water P2= OF 16 MPa T2=70°C P4-P2 Throttle (adinbatic) Compressor ladiabatic) Fan PS = P13 Pl=400 Pa at vapor air flow Tair =-10°C
9. The preservation of foodstuffs by refrigerating is an expensive process, butthe canning process is more expensive than refrigeration. Ills?
5. A boot strap cooling system of 10 tons is used in an aeroplane. The temperature and pressure conditions of atmosphere are 20°C and 0.9 atm. The pressure of air is increased from 0.9 atm to 1.1 atm due to ramming. The pressures of air leaving the main and auxiliary compressor are 3 atm and 4 atm respectively. Isentropic efficiency of compressors and turbine are 0.85 and 0.8 respectively. 50% of the total heat of air leaving the main compressor is removed in the first heat exchanger and 30% of their total heat of air leaving the auxiliary compressor is removed in the second heat exchanger using removed air. Find:a) Power required to take cabin loadb) COP of the systemThe cabin pressure is 1.02 atm and temperature of air leaving the cabin should be greater than 25°C. Assume ramming action to be isentropic.
01. A refrigerant 22 system having a refrigerating capacity of 55 kW operates with an evaporating temperature of 5°C and rejects heat to water cooled condenser. The compressor is hermetically sealed. The condenser has a U value of 450 W/m².K and a heat-transfer area of 18 m? and receives a flow rate of cooling water of 3.2 kg/s at a temperature of 30°C. What is the condensing temperature?
IDENTIFY THE FF: AIRCONDITIONING AND VENTILATION 1. Acts as a master controller which keeps the system inautomatic operation2. Adds heat to a fluid3. Ratio of the actual partial pressure of the watervapor in a space to the saturation pressure of purewater at the same temperature.4. Also known as the heat content of air-vapormixture5. Temperature as read on an ordinary temperature6. Temperature where in water will start to condense7. Equipment that removes heat8. Is the process of treating air9. Their purpose is to create atmospheric conditionsfavorable to human health, comfort and efficiency.10. The system is to maintain indoor conditions forwinter season
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Additional Instructions: Define each enthalpy obtained from tables and chart and draw the p-h diagram labeling the respective evaporating and condensing pressures and temperatures in each problem. Simple Vapor Compression Refrigeration System 53 PROBLEMS (1) An ammonia vapor refrigeration cycle operates at an evaporator temperature of-16 C and a condensing temperature of 32 C. Determine the coefficient of performance (a) for an ideal saturation eycle, (b) for wet compression with saturated vapor leaving the compressor, and (c) if the vapor at suction to the compressor is superheated 6 degrees. Ans. (a) 4.50, (b) 4.70, (e) 4.28