1. Modeling analysis of solar collector

We also analyzed the types, sizes, colors and textures of the main solar collector products on the market.

(1) Types of solar collectors. At present, the solar collectors in the Chinese market mainly include flat-plate solar collectors and vacuum tube solar collectors. The latter is also divided into all-glass evacuated tube collectors, U-tube type evacuated tube collectors and heat pipe type evacuated tube collectors. All-glass vacuum tube collectors account for the vast majority, and the use of flat-plate collectors is gradually being promoted.

(2) Dimensions of solar collectors. “Flat-plate solar collectors” (GB/T6425-2007), “Evacuated tube solar collectors” (GB/T17581-2007), “All-glass vacuum tube solar collectors” (GB/T17049-2005) respectively stipulates the dimensions of flat plate collectors and the size of collector tubes of vacuum tube collectors. Appendix B of “Evacuated Tube Solar Thermal Collector” (GB/T17581-2007) gives the recommended outline and plane dimensions of the vacuum tube solar thermal collector.

The size specifications of some brands of solar water heaters on the market are as follows:

·Flat plate collector: the common specification is 2000mm×1000mm, and the thickness is 75~95mm. The specific size can be designed according to the requirements of the building module.

·Evacuated tube type solar collectors (U-shaped tube, heat pipe type): There are many specifications of the collector, the length is mostly 1700~2500mm, the width is 1200~2000mm, and the thickness is about 150mm. The size of the collector tube is mostly the recommended size, with three diameters: d47, d58, and d100, and the length is 1200~2100mm.

(3) Color of solar collector. The color of the collector is mainly determined by the solar absorbing coating on the heat absorbing surface. Solar absorbing coatings can be divided into two categories: non-selective absorbing coatings and selective absorbing coatings. The former refers to an absorbing coating whose optical properties are independent of the radiation wavelength, and the absorption rate of solar radiation is equal to the infrared emissivity. The latter refers to absorbing coatings whose optical properties vary significantly with different radiation wavelengths, pursuing the highest possible solar absorption rate and the lowest possible infrared emissivity. Non-selective coatings include black nickel, black chrome, black paint, etc. This kind of coating is simple to operate and can effectively absorb solar energy, but at the same time, the higher long-wave radiation makes the collector have a larger heat loss. For example, the solar absorption rate of blackboard paint is as high as 0.95, and the emissivity is also around 0.9. The selective absorption coating can be prepared by various methods, such as spraying method, chemical method, electrochemical method, vacuum method, magnetron sputtering method, etc. The selective absorption coating prepared by this method has an absorption rate of 0.93-0.95 and an emissivity of 0.12-0.04, which greatly improves the thermal performance of the product.

Color solar collectors used abroad are rarely used in China.

(4) Surface texture of solar collector. The surface of the solar collector is generally glass (matt, polished). The flat-plate collector is in the shape of a plate, and the surface is mostly cloth, matt, frosted glass, and the texture is relatively soft. The evacuated tube collectors have a tubular and grid-like texture, and the arrangement of large-area evacuated tube collectors can also show a plate-like texture. Glass tubes are mostly polished, and there will be strong light reflection. The plate-like shape of the flat-plate collector and the grid-like texture of the evacuated tube collector have a certain corresponding relationship with ordinary building components.

2. Combination method

Through the analysis of the modeling of high-rise residential buildings and solar collectors, and find the relationship among them, from the perspective of aesthetics, put forward the following several combined design ideas, so that the collector becomes a part of the architectural modeling, to achieve the requirements of aesthetics.

(1) Strengthen the sense of rhythm and rhythm. Due to the functional characteristics of high-rise residential buildings, some building components are often repeated, such as balconies and windows. The interval repetition of balconies or windows on the façade and the changes in the number, spacing, and direction of the combination can make the viewer’s line of sight produce a dynamic rhythm extending up and down, left and right, combined with the changes in the volume, forming a sense of rhythm and rhythm. The collector can be combined with these building components to form a certain regular arrangement and combination on the facade to form a sense of rhythm. Appropriate local changes can also increase the richness and liveliness of the facade (as shown in Figure 1).

(2) Strengthen the vertical shape. High-rise residential buildings, especially tower-type high-rise buildings, will use vertical and straight lines to emphasize the vertical upward feeling. When the collectors are arranged on the facade, they can be arranged centrally and continuously, or combined with windows and balconies to form vertical divisions, emphasizing vertical lines (see Figure 2).

(3) Facade texture changes. Solar collectors have a special color and texture. The combination of the flat-plate soft texture of the flat-plate collector and the grid-like texture of the evacuated tube collector and ordinary building materials increases the changes in facade materials and enriches the building facade texture. At the same time, the collector can form a certain shadow on the building facade, which increases the contrast between the virtual and the real in the shape and the layering of the space (see Figure 3).

(4) Color coordination and contrast. The facade colors of residential buildings are generally softer, such as milky white, light yellow, brick red, etc., which give people a warm and friendly feeling. Small areas of high-purity colors are also used to increase the liveliness and richness of the overall facade. Solar collectors are generally blue-black and blue-violet due to the use of absorbing coatings. Whether it is installed in a large area or scattered, its own color can also become an integral part of the color of the building facade. It can be coordinated with other building components, such as window frames, railings, glass, etc., or contrast with large areas of light-colored building walls.

Read more: Specific combination method of solar collector and high-rise residential appearance