Refrigeration and Air Conditioning 3 E Part 6 pdf

... 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., for...

Ngày tải lên: 12/08/2014, 00:20

... measurement 36 7 References 36 9 Index 37 3 vi Contents The refrigeration cycle 15 The total cooling effect will be the heat transferred to the working fluid in the boiling or evaporating vessel, ... Carnot Temperature Pressure Temperature Pressure COP Ideal reversed –5°C 4.24 35 °C 13. 68 3. 23 6. 70 Carnot Modified reversed –10°C 3. 54 40°C 15 .34 4 .33 5. 26 Carnot, ∆ T = 5 K...

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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 ... 100.0 Pump/compressor (electricity) 0.1 30 .0 Low-grade heat 165 – Heat rejected 265 .1 130 .0 The absorption system can be used to advantage where there is a cheap source of low-grad...

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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, ... (see Figure 6. 6). 6. 6 Evaporative condensers This cooling effect of the evaporation of water can be applied directly to the condenser refrigerant pipes in the evaporative condenser (Figur...

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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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... 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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... 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 ... an estimate of unknown figures, or the process analysed to decide representative rates. Assumptions should be stated and agreed by the parties concerned, since these estimates...

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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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... 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 Sensitive and ... 500 diameter 6 Fan 500 diameter – 1 .3 7 Enlarge 500 diameter to – 1 .3 3 .61 7.8 0.4 3. 1 34 .1 26 .3 60 0 × 60 0 8 Duct 60 0 × 60 0 8 1 .3 3 .61 7.8 0.2 1 .6 31 .0 23....

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... 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 the UK, where ... in the UK at the present time is where air cooling is required in the summer and air heating from the same piece of equipment in the winter. The alternatives will be electric resista...

Ngày tải lên: 12/08/2014, 00:20