Solar radiation can have thermal and photochemical effects on industrial products exposed outdoors, which can adversely affect the performance and operational reliability of industrial products. According to the requirements of environmental test standards for some industrial products, solar radiation should be carried out before these products are developed and finalized. Test to assess its adaptability to the solar radiation environment and operational reliability. The solar radiation test chamber is a laboratory for artificially simulating the solar radiation environment indoors and conducting solar radiation tests. The solar radiation test room uses special lamps to simulate the changes of solar radiation spectrum, radiation intensity and sunlight intensity. Therefore, the indoor lamps have a large amount of heat, and the heat generation varies greatly with time. At the same time, the indoor temperature is also required to change according to a certain curve to simulate the temperature change in the summer day. The maximum room temperature requirement is 40-50°Q. Therefore, the solar radiation test room is also a high temperature environment test room. For high-temperature environmental laboratories, in order to achieve and maintain high temperature environment in the room, air-conditioning systems usually need to be heated, so strengthening the building insulation performance can generally reduce the heat load and energy consumption of the air-conditioning system, and enhance the building insulation performance, which is currently the building energy-saving design. An important way. However, due to the large amount of heat generated by the indoor lighting of the laboratory, the heat insulation performance of the building will weaken the heat dissipation capacity of the building to the outside, thereby increasing the cooling load of the air conditioner. Increasing the building insulation performance of the solar radiation test room is beneficial to reduce the energy consumption of the air conditioner. This is an important technical problem to be solved in the design work of the solar radiation laboratory. In the aspect of solar radiation simulation technology, the previous research mainly focused on the discussion of test parameters. 1 Through the retrieval of some common databases at home and abroad, there is no report on the research on the insulation of the building envelope of solar radiation simulation laboratory. The computer simulation analysis method simulates the relationship between the building thermal insulation performance of the solar radiation laboratory and the air conditioning heat and cold load and energy consumption, and provides a scientific basis for the building thermal insulation design of such buildings.
1 Laboratory overview and technical conditions A large solar radiation laboratory can simulate solar radiation indoors according to the relevant standard 4', and conduct solar radiation test of large and medium-sized equipment. The largest test piece is 60 steel. The indoor temperature requirement is changed according to three different curves to simulate the temperature change of typical summer days in different climate zones. See the three room temperature curves. The test was carried out in a cycle of 24 hours, usually 3 to 7 cycles. The interior uses special lamps to simulate the spectrum and radiation intensity of solar radiation. The radiation intensity of the lamps changes according to a certain curve to simulate the change of solar radiation intensity within one day. The total heat generation curve of solar radiation simulation lamps is seen as the comprehensive luminous efficiency. 40%. According to the indoor building area, the heating index of the lamp is up to 1100W/rf. It can be seen that the heating intensity of the indoor lamp is very large. The laboratory does not require indoor humidity and there is no source of moisture in the room. The air conditioning system is heated by electric heating, and the cooling is performed by outdoor air ventilation cooling and water spray evaporation. The building wall structure is 200 thick reinforced concrete + polyurethane foam insulation layer, and the surface is 1 thick stainless steel plate.
2 Air conditioning load calculation method The air conditioning cooling load of the laboratory mainly includes the cooling load of the building envelope, the cold load of the test piece, the cold load of the lamp, the cold air load of the infiltration, and the cooling load of the circulating fan.
21 Air conditioning load calculation of building envelope and test piece During the solar radiation test, the indoor temperature is constantly changing, so the thermal change process of the building envelope and the test piece is an unstable heat transfer process. More complicated, the finite difference numerical algorithm is used for calculation. The one-dimensional large flat plate heat transfer calculation adopts the forward difference format, and is divided into N equal parts in the thickness direction. The heat transfer difference equation is the input point and the first point. The temperature of the time node; n0 is the initial temperature; the outer wall temperature; t is the indoor wall temperature.
The boundary conditions on both the inner and outer sides of the building envelope are the third type of boundary conditions, and the outer wall faces the heat release coefficient; an is the internal wall facing the heat release coefficient.
The building envelope structure is generally a multi-layer composite insulation structure consisting of a structural layer and a thermal insulation layer. It is assumed that the kth thickness node is the interface node of the two materials. According to the heat balance, the interface conditions can be obtained: the thermal conductivity and density of the material. And specific heat capacity. The interface temperature for the first time node.
The heat transfer difference equation of each thickness node of each layer, the interface condition equation between each layer of materials and the boundary condition equations of the inner and outer surfaces are combined to obtain the angular solution to obtain the temperature field of the multilayer composite thermal insulation structure during the whole test. Change and heat transfer conditions. The various components of the building envelope, including the wall, the ground, the roof, the door and the test piece, have different material compositions and structures, so the temperature field is calculated by the finite difference method. Since the specimen test chamber is varied, indeterminate, in order to simplify the maximum is calculated according to the average thickness of the test piece, the test piece is processed into a shell-dimensional calculation. The meteorological parameters are calculated according to the local meteorological parameters of the building. The outdoor calculated temperature of the air conditioning in winter is 256 °C, and the outdoor calculated temperature of the air conditioning in summer is 31.8 °C. The winter and summer conditions are calculated separately. Considering the most unfavorable situation, the indoor temperature curve of the winter working condition is calculated according to the test curve 1 with the highest temperature, and the indoor temperature curve of the summer working condition is calculated according to the test curve 3 with the lowest temperature.
22 lamps and air conditioning cooling load calculation The heat generated by the luminaire consists of two parts, one part is convection heat and the other part is radiant heat. According to the data provided by the luminaire manufacturer, the convection heat of the luminaire accounts for about 60% of the convection heat directly forming the air conditioning cooling load. Radiant heat lamps proportion of about 40% of the heat required by this part of the radiation absorbing surfaces of the inner envelope and the outer surface of the test piece was heated, in order to form the cooling load heat, which cooling load is calculated according to the cooling load coefficient Since the laboratory heat when the lamp is gradually changed, and therefore the light units of 1h heat radiation amount discrete time-division process, paragraph by paragraph, the cooling load calculation results and the time-superimposed, heat radiation lamp to give the total hourly air-conditioning cooling load, heavy-duty type room, the cooling load of the heat radiation coefficient 1h light data of table 1 is calculated by 161. the analysis showed that cold load factor calculating a turn-on time discretization algorithm using this comparison The result is basically the same as the corresponding data in it, and the maximum absolute error is Q (H therefore this discretization algorithm is feasible.
Cooling load factor of light-on time Table 1 Cooling load coefficient of heat dissipation of lamps (lighting time is 1h) 23 Calculation of permeate air load and fan cooling load The area of ​​the gate of the laboratory is large, and the sealing performance is poor. 1 time / h calculation, because the laboratory relative humidity is not required, the air conditioning system uses ventilation cooling, there is no dehumidification process, so the air conditioning cooling load of the infiltrated air only calculates the sensible heat load. Laboratory circulating fan of the air conditioning system during the test power of 24kw fan is continuously operated, so heat dispersion of this calculated instantaneous cooling load.
3 Calculation results and analysis of the polyurethane foam insulation layer of the building wall and roof at different thicknesses, the simulation calculation results of the air conditioning heat and cold load of the laboratory in winter and summer conditions are seen under summer conditions (insulation thickness is 100) consisting of air-conditioning cooling load accumulated see summer conditions cumulative heat load of 0 analysis of these calculations are as follows where the negative thermal analysis summer air conditioning conditions, the total heat load of the air conditioning system does not require heating 0. Under winter conditions, it can be seen that when the insulation thickness is less than 100", the air conditioning system needs to be heated. When the insulation thickness is greater than 10mm, the air conditioning system does not need to be heated.
(2) The increase of the influence of building insulation on the air conditioning energy consumption in summer conditions will make the air visible. Under the summer conditions, the thickness of the insulation has little effect on the energy consumption of the air conditioner, and the energy consumption is slightly increased. The thickness of the insulation is 250. The accumulated cooling load of the air conditioner is only increased by 1% when the thickness of the heat preservation is 50. It can be seen that in the cumulative cooling load of the air conditioner in summer, the cumulative cooling load of the luminaire is the largest, and the cumulative cooling load of the circulating fan is also large, and the enclosing structure is It plays a role in heat dissipation. Due to the small indoor and outdoor temperature difference in summer working conditions, the heat transfer capacity of the envelope structure is small compared with the lamp load, so the insulation performance of the envelope structure has little effect on the air conditioning load and energy consumption in summer.
(3) Influence of building insulation on air conditioning energy consumption in winter working conditions Because the indoor lamps of the building have a large amount of heat, even in winter conditions, the required cooling capacity is much larger than the required heating amount, and the cooling is still an air conditioning system. The main task. Under the winter working conditions, when the thickness of the insulation layer is less than 100 mm, the increase of the insulation thickness will increase the cumulative cooling load of the air conditioner and reduce the cumulative heat load. When the thickness of the insulation layer exceeds 100, the cumulative heat load is increased by 0. The insulation thickness has no effect on the heating energy consumption, but the air conditioning cooling energy consumption in winter and summer conditions is increased. Therefore, the insulation thickness should not exceed 10 mm. Using outdoor free cold source for cooling, the main goal of energy saving in winter working conditions is to reduce the electric heating capacity of the air conditioning system. Therefore, the reasonable insulation thickness should be 100 when the building insulation thickness is 10mm, and the air conditioning in the summer and winter conditions is cold. Seeing and changing the load on a time-by-time basis can be seen from the results of these calculations, whether it is winter or summer conditions, the test time is 13:00, the air conditioning cooling load is the largest. Therefore, during the test, the initial time of the test is set at 4:00 pm, and the maximum air conditioning cooling load occurs at 5:00 am. This is the lowest outdoor temperature. It can make full use of the outdoor natural cold source and perform ventilation cooling to reduce Air conditioning energy consumption.
Test time / h air conditioning cold load under winter conditions Fig. test time / h air conditioning cold load under summer conditions Fig. 4 Conclusion Solar radiation test room has indoor heating heat, large room temperature and luminaire heat change, envelope structure The complex characteristics of thermal conditions change and improve the insulation performance of building envelopes to reduce the air conditioning energy consumption. This is an important technical problem that is not solved in the design of solar radiation laboratory. In this paper, the computer simulation analysis method is used to simulate and study the relationship between building insulation performance and air conditioning heat and cold load and energy consumption. The research results show that: due to the large amount of heat generated by the lamps, even in winter conditions, the required cooling capacity It is still large, and the amount of heating required is small. The increase in building insulation performance will reduce the energy consumption of air conditioning heating, but it will increase the energy consumption of air conditioning cooling. Therefore, blindly increasing the thickness of insulation will not only increase the investment in building insulation. Moreover, the total energy consumption of the air conditioner will increase. For the subject studied. When the thickness of the polyurethane foam insulation layer of the building envelope is 100% thick, the increase of the thickness of the insulation layer will increase the total energy consumption of the air conditioner r994-2UT6CnmaAcaaemicoumaTErectromc, and the reasonable thickness of the insulation layer is 10mm. These findings provide the solar thermal insulation laboratory building insulation design. An important basis.
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