Refrigeration and Air Conditioning 3 E Part 5 ppt

... fluid entering the cooler, not the log mean temperature difference (see [1 5] ). In systems where the evaporator cools air, the air itself becomes the heat transfer medium and its temperature and ... 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...

Ngày tải lên: 12/08/2014, 00:20

... 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

... 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 Modified reversed – 15 C 2.96 45 C ... recovery 32 0 31 Control systems 32 4 32 Commissioning 33 3 33 Operation. Maintenance. Service. Fault-finding. Training 33 8 34 Efficiency and economy in op...

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 ... 100.0 Pump/compressor (electricity) 0.1 30 .0 Low-grade heat 1 65 – Heat rejected 2 65. 1 130 .0 The absorption system can be used to advantage where there is a cheap source of low-g...

Ngày tải lên: 12/08/2014, 00:20

... 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, ... between 85 litre and 2 85 litre must have one such relief device. Those below 85 litre but larger than 76 mm inside diameter may have a fusible plug to relieve pressure in a fire. Manufact...

Ngày tải lên: 12/08/2014, 00:20

... 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...

Ngày tải lên: 12/08/2014, 00:20

... 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 ... pressure and temperature. The relationship between temperature and pressure for 3. 5 and 5 volumes is shown in Figure 17.4. It will also be affected by the amount of air alrea...

Ngày tải lên: 12/08/2014, 00:20

... estimation 2 15 ∆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 selecti...

Ngày tải lên: 12/08/2014, 00:20

... 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...

Ngày tải lên: 12/08/2014, 00:20

... 53 7 2 75 44 39 35 36 2 22 Sept. and 10 am 34 51 35 7 52 4 38 0 54 46 40 477 and 22 Sept. 11 am 35 54 182 4 53 442 161 49 42 54 4 22 March 12 noon 35 53 71 32 7 467 32 7 71 53 56 5 North latitude 1 pm 35 ... 1 pm 35 42 49 161 442 4 53 182 54 54 4 South latitude 2 pm 34 40 46 54 38 0 52 4 35 7 51 477 3 pm 31 35 39 44 2 75 53 7 481 109 36 2 4 pm 26 27...

Ngày tải lên: 12/08/2014, 00:20