Solar hot water project and air source heat pump unit

Three years ago, we designed and installed a solar thermal water supply project with a daily output of 30 tons of hot water at a major hospital in Beijing. Many users from the return visit, the use of very good, 365 days a year, more than 30 tons of hot water per day, the water temperature not lower than the set 45 ℃. Since urban areas in Beijing have long ago banned the burning of coal boilers, many units switched to gas boilers, fuel costs increased severalfold, making the operating costs of enterprises increased.

From the perspective of environmental protection, the policy of changing coal to gas is beneficial to the society and the benefit of the people. From the operating cost of gas-fired boilers, the cost of enterprises indeed increases a lot. Therefore, from the solar collector water supply and heating engineering unique environmental and economic point of view, is indeed a lot of work, from our design and installation of the project, enough to see the environmental effects of their social effects and economy as a business Generate huge economic benefits.

This solar hot water project in the early design, we carefully re-mapping according to the design drawings of buildings (many buildings during construction, many times to modify the construction drawings, the actual size and drawings often have gaps), the modified part will be changed Re-mark, easy to design the accuracy of the size of each part, in order to facilitate the final assembly work. In the middle of the building facing the best location, there is a large elevator room, so that the morning sun some east, the western part of the impact of sunshine; the afternoon sun some west, the eastern part of the impact of sunshine. When the building area is very limited, only to consider the maximum use of its construction area, according to the traditional method of installation of solar water heating, according to the latitude calculation of manifold angle, but also between the header to keep A certain space, to prevent the shading of the problem of occlusion, combined with the shape of the building is a complex multilateral geometry, very irregular, with a certain degree of design and construction difficulty.

After the calculation of the hospital construction area of ​​about 570 square meters, minus the elevator room and the shadow of the engine room and behind more than 20 air-conditioning units, the actual usable area has less than 500 square meters. At that time, the national standard "solar hot water system design, installation and engineering acceptance of technical specifications" GB / T18713-2002 Although it has just been made but has not yet been announced. We refer to the relevant information from other countries and see that many countries have already adopted horizontal or small-angle installation methods. Looking at it in translation, we think that there is a certain truth. Such as:

1, from the fluid mechanics analysis, the flow of water is more smooth, so the loss along the way is relatively small.

2, the collector system up and down transition path is very small, so difficult to have a vacuum tube deposits.

3. In the northern summer months, the morning sun rises from the northeast corner, and from the northwest corner in the evening is a conventionally installed inclined solar collector that hovers behind or on the collector for a few hours . The sunlight can be understood as parallel light, the vacuum tube is circular, most of the season horizontal exposure also illuminates 180 º, one day sunshine longer, so can increase the heat absorption of the sun (southern China has little effect, should pay attention to the north The local winter solstice season vacuum tube sunlight blocking angle of winter sunshine radiation is weak, and the summer difference between the more the more the more obvious north).

4, the utilization of the top area of ​​the building can be as high as 80%, and the top of the building is more evenly loaded.

We have installed in the past according to several solar water heating projects in the South, using a 0 ~ 30 ° installation, the use of about a year or so, operating conditions and the user to reflect all the good. Therefore, all the design work can only be considered in this limited area, we will irregular area is divided into different sizes of rectangles, divided into two according to the general area of ​​the flow loop, the width of each loop can only be divided into Two-way parallel. Using series and parallel combination, the total heat collection area reached 400 square meters. Although most of the sunshine conditions in spring, summer and autumn are sunny under the influence of the elevator engine room, most of the temperatures are in the range of 50 ° C-75 ° C, and the overall thermal efficiency is still satisfactory. When the sunshine conditions are not good In winter, due to the use of air-source heat pump unit with output of 100KW as auxiliary energy, the water temperature can be set as needed.

Designed for 30 tons of storage tank heavier, from the architectural mechanics considerations, placed in the top of the building is clearly unreasonable. Allowable use of space The circulation lines are only slightly increased in the basement of the hospital, but we have a positive side on auxiliary energy equipment. In the vicinity of the basement tanks are condensate tanks and pumping stations in the boiler room, and in winter Damp heat needs a lot of daily discharge, which gives the use of heat pump units to create the conditions. In the spring, summer and autumn seasons, the heat pump unit can utilize the weak heat in the atmospheric environment and produce high-grade heat energy through the compressor with a small amount of electric energy. In winter, the heat pump unit can absorb heat and heat from the boiler room pump room, Heat at the same time, the condensate through the pipeline connected with the pump automatic drainage system, ready to be discharged, the pump room air is also dry, heat has also been fully utilized, serve two purposes.

We use the heat pump unit input power of nearly 27KW, output 100KW of heat, but also produces about 90KW of air-conditioning in the summer, you can also receive access to the various logistics around the use of the department. In short, the energy efficiency of heat pump unit is about 1: 3.5 or so, at the same time, you can get about 3 times the air-conditioning. In short, when the input is 1, you can get 6 ~ 6.5 times the benefits. The efficiency of the heat pump unit in the solar hot water project in the hospital has been fully utilized.