Views: 15 Author: 1stsunflower Publish Time: 2019-11-22 Origin: Site
The solar collector module is the most mature and widely used solar thermal utilization device. The main uses are hot water, floor heating, swimming pools, seawater distillation, drying, power generation and air conditioning refrigeration systems. The heat transfer medium may be water or gas or the like. When the solar collector module is used in a refrigeration system, the pressure will reach 30 bar, which will require redesigning the construction of the solar collector module.
The customer wants to use the heat generated by the solar hot water system to heat the gas. The specific requirement is to achieve 15-20kw of power. The pipeline can withstand a pressure of 30bar and the temperature rises from 10°C to 15°C.
This is the size of their pipe given by the customer. The solution we have given is as follows:
According to the data provided by the customer, the total heat required to heat the temperature by 10 °C with a collector and work for 1 hour is: 0.6337kg/s*3600s*1.473kJ/kg oC*10 oC=33604kj
33604kj /3600000=9.3KW,
In other words, a 9.3 kW solar collector is required.
1 set SFB305818 (30tubes) solar collector, when the solar radiation reaches 1000W/m2, its power can reach 1.8KW.
9.3KW/1.8KW=5.2 units.
If you use a collector to heat the temperature rise 15 ° C, you need 7.8 SFB305818
Since the solar radiation intensity changes during the day, it is the strongest at noon and the worst in the morning and evening.
We recommended to install 8-10 SFB305818.
The connection diameter of both ends of the solar collector is 22 mm, and the diameter of the intermediate runner portion is 35 mm.
The working pressure required by the customer is 2.85 MPa. According to this requirement, the thickness of the copper tube of the solar collector is calculated as follows:
S≥2.85Mpa(0.2+35)/2*41.2Mpa=1.22mm
We recommend using a 1.5mm thick copper tube as the flow path for the solar collector.
The customer is very satisfied after seeing the plan, but he also has two questions.
1. He wants to use a U-tube collector, we recommend a heat pipe collector (picture below)
In fact, the U-tube collector does not meet his requirements, because the copper tubes inside it are connected, so when the heat is transferred, one collector needs to pass 108 meters, and eight collectors need to pass 864 meters. The heat loss is huge. The heat pipe collector only needs to pass 19.2 meters.
But the customer understands that the longer the distance travels, the more heat is absorbed.
During the passage of the gas over such a long distance, only heat is lost. The efficiency of the heat pipe is high and the gas is heated sufficiently as it passes. The U-tube and heat pipe system are virtually identical. The flow path is equivalent to the oven. The gas can be heated as long as the heat of the heat pipe can be transferred to the flow path.
The U-tube has a long pipe, so the heat is relatively dispersed and the temperature is not high. On the contrary, since the heat pipe is high in efficiency and the flow path is short, the gas can be heated well in a short time.
2. Worried about whether it can withstand a pressure of 28.5 bar.
The working pressure required by the customer is 2.85Mpa, and the thickness of the copper tube of the collector is calculated as follows:
S≥2.85Mpa(0.2 + 35)/2*41.2Mpa=1.22 mm
We recommend using a 1.5mm thick copper tube as the flow path for the collector.
After our calculations and explanations, the customer finally accepted our plan, and the system is now working properly and meeting the customer's requirements.
If you need to design such a solution, please feel free to contact us.
