Refrigeration and Air Conditioning 3 E Part 13 ppsx

... higher condensing temperature will be a drop in the refrigerating effect, since the liquid enters the expansion valve hotter, and a decrease in volume pumped due to the lower volumetric efficiency. ... separate budgets, possibly accounted for by four different managers, so these budgets need to be adjusted. Separate fuel meters are needed to prove the savings, which might otherwise be held...

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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 ... determined by the requirements of the air conditioned enclosure. BS 56 43: 1984 The refrigeration cycle 23 Low-temperature compressor Low-temperature condense...

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... 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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... covered by the provisions of BS.4 434 :1980 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 temperatu...

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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 118 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 b...

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... have to be installed on site. 13. 3 One-piece packages The true packaged unit will have all the parts of the system and will be factory tested in the complete state. There are four basic types: 25°C 30 °C 35 °C 40°C ... 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., fo...

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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 ... plate freezers. Health and safety requirements continue to become stricter in the maintenance of the cold chain and the latest regulations should be adhered to. 178 Refrigeration an...

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... are based on observed practice. The parameters are the size of the store, the enthalpy difference between inside and outside air, and the usage of the doors. The latter is affected by the existence ... 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 of the re...

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... condenser to re-heat, together with the energy supplied to the compressor and the fan motor (since the latter is in the airstream). Figures for this electrical energy will have to be determined and ... factor is therefore one of wet bulb rather than dry bulb temperature, and the closer the upper limits are approached, the less heat can be rejected and so the less work can be done. 23...

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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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