Analysis Of Measurement Error And Wall Thermal Performance Measurement In Solar Greenhouse

Heat transfer coefficient is an important parameter to measure the thermal characteristics of the wall. So accurate measurement of heat transfer coefficient of the building envelope is essential for the research of the thermal characteristics of the wall. There are many methods of on-site testing of transfer coefficient. Thermal infrared imaging; Hot box; Plane thermal power method and heat flow meter. But Heat flow meter is the most authoritative and the easiest method. Although heat flow meter method have some advantages, heat flow meter has a large measurement error. So how can reduce measurement error is very important to measure the thermal characteristics of the wall. This test based on heat flow meter method, takes ordinary clay brick greenhouse, porous brick greenhouse and fly ash brick greenhouse which the north wall material is different as our research target. Our purpose is to research the influence of heat flow meter arrangement position; paste surface; masonry mortar joint thickness on the wall heat transfer coefficient error. In addition, we also analyze the accuracy calculated by different calculation methods. And also we take advantage of Finite difference method and Finite element volume calculating the heat flow in inner surface of each wall, then comparing to the measurement value. Furthermore, reach conclusion the accuracy of different calculation methods. Finally, provide a theoretical basis for heat flux measurement in greenhouse. The results show that:1. Heat Flow Meter random arrangement position has a great influence on the heat transfer coefficient errors. For ordinary clay brick greenhouse, when the heat flow meter is located on the center of block, there is a small error,16.62%. For porous brick greenhouse and fly ash brick greenhouse, the minimum error lies in position 1/4 of block, measurement error respectively 26.84% and 21.07%.2. Heat flow meter test surface has a great influence on the heat transfer coefficient errors. We have come to the double-sided heat flow meter test error is less than one-sided Heat flow meter test error. In ordinary clay brick greenhouse and porous brick greenhouse, double-sided heat flow meter test error reduced by 3 times compared with one-sided flow meter test error. In fly ash brick greenhouse, the two test method is not significant.3. Compared with arithmetic mean method, the error is reducing by 3%-10% calculated by dynamic analysis.4. When heat flow meter is arranged on the ash seam thickness of 15mm×15mm, the heat transfer coefficient error is the minimum. The heat transfer coefficient of error increases with the increase of the thickness of the mortar joint.5. There is a high consistency between measurement and calculated by Finite Difference Method and Finite Volume Element Method. In summer, the finite difference method and finite volume method can well simulate the heat flux both the north and the east wall. But for the west wall, the error is large. In winter, the two methods can well simulate the flux of east wall. Finite difference method can simulate heat the western wall. For the north wall, the error is large.