暖通空调设计--暖通英才网(国外英文资料).doc

暖通空调设计--暖通英才网(国外英文资料)HVAC design - HVAC excellence networkCold and heat sourceTheA cold source, "heating ventilation and air conditioning design specification" GBJ1987 chapter sixth "refrigeration" units should not be too much, with the air conditioning load and the changes of operation regulation to meet the requirements, the number should not be less than two "provisions。 When we consider the chiller configuration, we should avoid the following four cases。To avoid a number of units is too small, too small number of the problems are: the(1) load reliability decline, once the peak load when the unit fails, the proportion of the impact is bigger;(2) poor load adaptability。

Because the building is often equipped with entertainment, the area is not large, the cooling load is not large, but the entertainment places and often advance and extend the cooling requirement, the number of units, means a single refrigeration load, once opened, can not adapt to the load, centrifugal machine group, often prone to surge phenomenon so, choose the centrifugal unit, to meet the 20% ~ 40% load can adapt to the needs of the minimum cooling load。 The(3) the number of units is too small, and the probability of low load operation of the unit is high。

As the unit operates under low load, the energy consumption of COP will be increased。 TheTwo avoid too many units。 The number of units have the following disadvantages:(1) the capacity of single unit decreased, COP decreased, the high energy consumption;(2) the number of units, the circulating pump configuration also, pumps in parallel, parallel the loss;(3) the number of units is large, the circulating water pump is large, and the area occupied by the engine room is large。 TheThere is a situation in which the designer will sometimes chillers high low area separate, in fact this is not necessary, because the area can be used through the heat to make the cold water machine combination level area as a system, it can reduce the number of units。

The(4) excessive number of units, but also means an absolute increase in the number of failures。 TheThree to avoid inappropriate use of multi nose units (including multi head air-cooled heat pump or modular air cooling and heating pump, modular chiller)。 Such as 3 30HT - 280 24 head, 3 LSRF / 829M 36 head, 8 CXAH250, the total cooling capacity is only 1224kW, there are 32 heads, the absolute fault point too much。 TheFour, we should avoid the use of equal capacity units。 The unit capacity, room layout may draw neat, spare parts will be less, but the project often have a small load of different functional sites, such as the use of other units, it is easy to cause disadvantage load。

In fact, "" code for design of heating ventilation and air conditioning in a large refrigeration room, when the refrigeration quantity is greater than or equal to 1160kW (100 x 10 share 4 kcal / hour) of one or more sets of centrifugal chillers, the provisions should also set one or two smaller centrifugal refrigeration capacity, live plug or screw type compression refrigeration machine size capacity collocation。 TheAbout heat sources, here only a point of view on the use of electric boilers, common discussion。

TheIn the selection of heat sources, there seems to be a tendency now that some departments prefer to promote electric boilers。 First of all, electricity is high grade energy, converting it into steam, low grade energy 95 degrees or 60 degrees Celsius hot water use, but also the loss of transport, from energy use, it is not worth。 Secondly, for China, electricity is not "clean energy" or "environmental energy", because our country is nearly 80% coal-fired power generation, resulting in greenhouse gas emissions next to the United States, the world's second。

So, the more electricity, means more greenhouse gas emissions, which is a threat to human survival, is a "developing country" Chinese, should also have the responsibility and obligation to reduce greenhouse gas emissions。 In addition, the use of electric heating boilers, winter air-conditioning peak time consumption is higher than the summer power consumption of 3~10 times, can not help but pay attention to。 It is worth pointing out that popularizing ice storage and electric heat storage。

Ice storage is necessary for peak load regulation in summer,Ice in the valley and peak power when the power of melting ice, can solve the electric power sector needs to adjust, for users, can also reduce the refrigeration capacity, reduce the summer peak load, using peak valley electricity price difference in the recovery of the power sector, due to the ice cold storage increased an investment after (generally 1 to 2 years), but also can reduce the operating cost, the biggest benefit is the power sector, it is also good for users。

But the electric power storage, the electric power storage is the water temperature difference, heat regenerative effect is poor, in addition to heat storage tank with large volume, large area, storage and transportation of large heat loss, and power balance problems, namely the power load in winter are higher than that of summer ice storage power load of 3 ~ 4 times than conventional air conditioning (non ice storage) is more than 2 times, the ice cold storage has the advantages of greatly inferior。

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