Refrigeration and Air Conditioning 3 E Part 8 pot

... estimation 215 ∆T a = temperature decrease above freezing h l = latent heat of freezing c b = specific heat capacity below freezing ∆T b = temperature decrease below freezing Some of these components will be zero ... process analysed to decide representative rates. Assumptions should be stated and agreed by the parties concerned, since these estimates are to form the basis for the selection...

Ngày tải lên: 12/08/2014, 00:20

... contributes CO 2 emission to the atmosphere. The choice of refrigerant is therefore about the efficiency of the refrigerant and the efficiency of the refrigeration system. The less the amount of energy ... copper. This chapter is about the new refrigerants and the new attitude needed in design, maintenance and servicing of refrigeration equipment. 3. 2 Ideal properties for a refri...

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... Maintenance. Service. Fault-finding. Training 33 8 34 Efficiency and economy in operation 35 1 35 Catalogue selection 35 7 Appendix Units of measurement 36 7 References 36 9 Index 37 3 vi Contents The refrigeration ... load estimation 2 63 27 Air movement 2 73 28 Air- conditioning methods 297 29 Dehumidifiers and air drying 31 6 30 Heat pumps. Heat recovery 32 0...

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... covered by the provisions of BS.4 434 :1 980 and require safety pressure relief devices as outlined in Section 6.10. In cases where there is no shut-off valve between the condenser and receiver, ... the condenser heat. If the mass flow is reduced, the temperature rise must increase, raising the condensing temperature and pressure to give lower plant efficiency. In practice, the temperat...

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... and shorten the working life. 11.11 Site pressure safety tests Site-erected pipework, once complete, must be pressure tested for safety and freedom from leaks. Pressures will be 1 .3 times the 1 18 Refrigeration ... higher condenser pressure is to increase the compression ratio and so reduce the volumetric efficiency and increase the power. There will also be the effect of the gas...

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... provide an insulated and refrigerated enclosure suitable for the handling and storage of perishable goods, at some predetermined temperature. The shape and size of the cold store will depend on: 1. ... a eutectic solution, and these are frozen down by placing these elements in the domestic deep-freeze cabinet. Once frozen, they can be used in picnic baskets, etc., for the short-term s...

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... hygiene, or the cheese will be damaged. Some cheeses can be frozen for long-term storage, but must then be allowed to thaw out gradually and complete their ripening before release to the market. Other ... and the sheet material skins may be flat or profiled. When the panels are manufactured the mixture is injected between the inner and outer skins and expands to the thickness required...

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... this table. Convective heat loss will depend on the area of skin exposed, the air speed, and the temperature difference between the skin and the Figure 23. 5 Basic CIBSE psychrometric chart (Courtesy ... to give equivalent, corrected effective, globe, dry resultant and environmental temperatures, all of which give fairly close agreement. This more complex approach is required where a...

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... sides of the fan. Such treatment needs to be selected for the particular application regarding frequency of the generated noise and the degree of attenuation required, and competent suppliers ... connecting the inner and outer tappings to the ends of the manometer, the difference will be the velocity pressure. Figure 27.2 Vertical and inclined manometers Figure 27 .3 Pitot tube Sensi...

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... system is reversed, the heat exchanger which was the evaporator becomes the condenser and vice versa (see Figures 9.4b and 28. 11) and the flow of energy is also reversed. Reversing valves may be ... possible refrigerant leaks. Steam drives have also been used. The economics of the heat pump are dependent on the relative costs of the drive power and heat energy from other sources. In...

Ngày tải lên: 12/08/2014, 00:20