Technical Analysis of Air Source Heat Pump Unit Engineering

0 Preface

Air-source heat pump water chiller / heater unit, with no need to design a dedicated refrigeration room, no need to set the cooling water (cooling towers, cooling pumps, cooling water treatment device) system, water conservation, energy saving (especially in heating), reliable operation, maintenance Small amount, low noise, small impact on the surrounding environment, etc., are being used more and more in domestic construction projects, especially in the renovation and expansion of old buildings. In this paper, Beijing Disability Rehabilitation Center air-conditioning engineering design as an example, a comprehensive analysis of the building air-conditioning design, comparison, concluded that: in a similar change, expansion project, the use of air-cooled heat pump water heater unit is indeed Economic and reasonable program.

Figure 1 Project Results

1 project overview

Beijing Disabled Persons Rehabilitation Guidance Center is located in Chaoyang District, Beijing. The project was highly regarded by leaders and relevant departments at all levels for being included in one of the 60 pieces of practical work done by the Beijing Municipal Government for the public in 2001. As the building has special functional requirements such as rehabilitation guidance and operation demonstration, it is required to build a demonstration project of leading technology and advanced equipment in provincial and municipal rehabilitation centers in China. Its construction area of ​​about 4000M2, is in the neighborhood near the original three-storey building on the basis of additional layer changes, expansion made. The project was completed in December 2001 and has been in operation for three years.

2 original program selection and determination

2.1 There are difficult to solve the problem

The original design adopted a centrifugal water cooling unit. However, during the design process, the following problems were not solved: firstly, about 120 M2 of cooling room area needed to be provided in the building; and the building had neither basement nor its building Around the refrigerator can not provide the location of the room, only in the building to find a solution, and in accordance with the use of rehabilitation guidance center division, the building area has been quite tight, can not be squeezed out of the engine room area. Second, the cooling tower can not be provided. However, as the building is located on the side of residential quarters, its building is more than ten meters behind a residential building. The problem of disturbing the residents is prominent, and the external operating conditions of the air-conditioning system are limited. The building can neither overshoot the back of the building, nor because of the noise caused by the residents around the dissatisfaction, in addition, the local structure of the local program with light body structure, simply can not load; third, because the building is a medical building, The heating time is longer than the surrounding residential building heating time, the extended heating time can only rely on the use of other heating methods to solve, and then built temporary boiler room was also subject to conditions. Faced with this situation, Party A had to consider another way.

2.2 program to determine

　　 Faced with this awkward situation, the construction side hopes that the design side will solve this problem. The construction side requires that the building be equipped with a centralized air-conditioning system. After careful consideration, after demonstration, the design side of the air-source heat pump using hot and cold water unit as a hot and cold source of the program to solve these problems solved. The building eventually chose two 100RT air-source heat pump chillers, which were placed open on the roof about 150 meters from the other side of the rehabilitation center to solve the problem of air-conditioning cold source occupancy. Only a light-weight 20-M2 room has been stowed on the roof of the center for the installation of circulating water pumps, winter heat exchangers, water separators, expansion tanks and other equipment. Figure 2 is the layout of the air-conditioning pump room layout.

Figure 2 Project Location Figure 3 heat pump unit location

Figure 4 air-conditioned pump room floor plan

3 economic comparison

3.1 cold source device itself economic comparison

In determining the cold source program, I have carried out several economic comparison of the cold source itself, the results of which are shown in Table 1.

Economic Comparison of Air-Cooled Chillers and Water-Cooled Chillers: Schedule-1

Not difficult to see from the table, air-source heat pump equipment, an investment is acceptable.

3.2 cold source equipment other than the economic and technological comparison

Evaluation of an air conditioning system, it depends on whether the system can meet the requirements of air conditioning building design parameters, the amount of one-time investment, but also should look at the installation, maintenance and operation and management costs, and the impact on the environment. Any kind of air-conditioning system can not be perfect, only by local conditions, can give full play to the function of an air-conditioning system. In the process of design and comparison, the author compares and evaluates the characteristics of air source heat pump hot and cold water chiller units and water chiller units for reference:

3.2.1 No need to set up a dedicated machine room, saving construction area.

This is particularly applicable in the expansion project, its economy is very significant. Take this project as an example; when the construction unit buys the building, the fee paid is about 8500 yuan / M2, only a reduction of 120 M2 air-conditioned room area is equivalent to saving 1.02 million yuan. If you do a one-off after the completion of the construction, the price will be 10,000 yuan / M2 or more, but also income of 1,200,000 yuan; even if not for sale, taking into account the dual social and economic benefits, only as a medical auxiliary supporting the use of housing, Its annual income is about 150,000 yuan, the economic benefits are very impressive.

3.2.2 omitted some of the equipment to reduce the management workload, but also solve the problem of noise nuisance

Air source heat pump system, eliminating the need for cooling towers, cooling pumps, cooling water treatment equipment, but also save a lot of trouble on the operation and management. Reduce the operation of equipment, reducing the operation and maintenance, repair work points, equal to improve the reliability of equipment operation, and even reduce management staff to save operating expenses. As a result of eliminating the cooling tower, cooling water pump to solve the noise on the surrounding environment interference and the impact of the problem, reducing the occurrence of conflicts and conflicts. We have conducted experiments on the interference of cooling tower and air-cooled condenser noise and found that people are accustomed to the wind noise brought by outdoor air-conditioners and are very sensitive to the water flow noise of the cooling tower.

3.2.4 air source heat pump heating operation, both convenient and economical

Air-source heat pumps in the northern part of the season for heating operation, it is the equipment's expertise, is any water-cooled units can not be compared. Taking the design as an example: As the building is a medical building for the rehabilitation of disabled people, heating up early and heating up later and the heating time will be longer than that of the society. This problem can not be solved when the original water-cooled unit was used for refrigeration. With the air source heat pump system, the transitional season can be directly heated. In addition, the air-source heat pump is more economical and energy-efficient than a conventional electric boiler, electric heating film and heating cable heating system (the COP of the energy efficiency is always less than 1) due to its energy efficiency COP of 2 to 4.5.

Figure 5 air source heat pump outdoor unit

3.2.4 Comparison of operating costs

About air source heat pump efficiency and operating costs, the discussion has been many, the air source heat pump air conditioning system, after nearly three years of operation, operating costs are fully controlled within the budget, and other similar buildings using different air-conditioning cold Compared with the heat source method, the operation cost was not obviously higher, but the performance of the expense was different. On the point of saving a limited amount of water resources, air-source heat pump hot and cold water unit's superiority is not to be questioned.

4 Conclusion

Through the case analysis of the above project, we can easily see the air conditioning heat source selection, the air source heat pump water heaters as the central air conditioning has a lot of advantages of cold and heat sources, such as high equipment utilization in the climate suitable area Winter and summer sharing, eliminating the boiler room and cooling water system, in line with China's water shortage conditions. In addition, the unit can be installed outdoors, saving the construction area of ​​the engine room. Air-source heat pumps simply draw heat from the air or release heat into the air, do not constitute air pollution and have little impact on the environment. Therefore, the unit has been widely used in small and medium-sized buildings. With air source heat pump energy efficiency COP value in the range of 2 to 5.5, high efficiency, energy saving, environmental protection will make the air source heat pump more widely used.

main reference:

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