How is the water temperature of the flat balcony wall mounted solar water tank not high

The weather is fine, but the water temperature of the balcony wall-mounted solar water has not been high, mainly due to the following reasons.

1. The ratio of heat collection area to water tank capacity is unreasonable.

The collectors of balcony wall-mounted water heaters include flat plate type, all-glass tube type, heat pipe type, and U-shaped tube type. Although solar energy is a clean energy, it has a low energy flow density, with a low energy flow of 17MJ ( .D), 1 100% of the solar heat throughout the day is converted into hot water (the temperature rises by 40 degrees), and it is only 102L.

Due to various factors such as the utilization rate of the lighting area of the collector itself, the thermal collection efficiency, the solar energy utilization area of the balcony, the light time of the balcony, the light intensity, etc., the heat gain from the solar energy is less than the design heat load, and the cold water temperature in autumn and winter is lower, but the bathing temperature is indeed higher, and the heat load increases, and the water capacity of the pressure water tank remains unchanged and the electric heating is not started, the solar heating water temperature will be lower than that in other seasons.

2. The heat transfer efficiency of the wall-mounted solar water tank heat exchanger on the balcony is low.

According to Fourier's law, the heat transfer efficiency is closely related to the heat exchange contact area, the medium flow rate, and the heat exchange material.

In terms of heat exchange area, the heat exchange area of the jacket and coil is larger than that of the small inner tank, in terms of medium flow rate, the forced circulation system is better than the natural circulation, and in terms of heat exchange materials, most of the jacketed water tanks with enamel liners are used, and the copper coil is better than the enamel coil.

3. The medium circulation pipeline is unreasonable.

At present, the balcony wall-mounted solar water heater is mostly a natural circulation system, and the natural circulation is that it does not require external power, and relies on the density difference of the system fluid itself to automatically circulate. However, the circulating water tank of the natural circulation system must be higher than the collector, and because the power formed by the density difference of the system fluid itself is very small, a variety of errors must be taken to reduce the circulation resistance of the system.

For example, choose a larger pipe diameter, make the pipeline as short as possible, and make as few bends as possible to prevent reverse slope and air blockage.

4. The thermal insulation effect of the heat collection system is poor and the heat loss is large.

In order to solve the problems of pressure bearing and frost resistance, the balcony wall-mounted solar water heater generally adopts the secondary heat exchange system, carefully does a good job in pipe insulation, and selects solar collectors with high thermal insulation performance to effectively reduce the heat loss of the solar collector part and significantly improve the efficiency of the system.