Scientists in China have analyzed the performance of a system that connects a heat pump heating system of the solar air with a thermal storage floor based on sand and have discovered that it can be an average indoor temperature of 18.8 ° C, even when outside temperatures vary from zz to 12.3 C.
Researchers from China have suggested combining solar air heat pumps (SASHP) with sand-based storage based on sand in rural clean heating projects.
“In rural areas where economic limitations and maintenance conditions are crucial, there is still a lack of research into the integration of cost-effective heat-oriented technologies with SASP systems,” the team explained. “Moreover, the performance and cost -effectiveness of such integrated systems have not been thoroughly investigated. In order to tackle the identified research slacuns, this article introduces a new thermal storage floor system that uses cost -effective, stable flush -filled coils, integrated with a SASP for rural heating. “
The academics have performed a series of tests in a real house in the inner Mongolia countryside, China. The building in which the system was installed was a single -family home in Chifeng, Inner Mongolia. The area has an abundant solar energy in the winter, with an average outside temperature of -3.4 C and the lowest temperature to -23.3 C. The heating season takes six months, from mid -October to mid -April.
The installed system included a solar thermal collector (STC), thermal storage tank (TST), Ashp, sand-based thermal storage floor (STSF) and water pumps. The STSF contains pipes with a layer of sand of 200 mm around the flushing layer. “When solar radiation is sufficient, the sand absorbs a considerable amount of heat and leaves it into the room. During the period of insufficient solar radiation or at night, the stored heat is gradually released in the room, extending the duration of solar heating, “they explained.
The system had four operational modes. Modus 1 was for sunny days, so that the system could only work with the STC to heat the TST. On a cloudy and rainy day, the system used fashion 2, which fully trusted ashp to heat the TST. Two modes were used for complementary heating: in mode 3 the STC works during the day and ASHP runs at night; While in mode 4 the STC works during the day and the ASHP is activated during the day on which solar radiation is insufficient, but the ASHP is not served at night.
The experimental system was measured 9 days from November 27 to December 6, 2023. “The STSF effectively maintains stable inside temperatures between 17.4 ° C at night and 20.2 ° C during the day, even with outside temperatures ranging from -18.4 ° C to 12.3 ° C (average -5.5 C). With an average performance coefficient (COP) of 2.6 and solar friction (SF) of 50.9%, the system appears to be a feasible solution for heating in severe cold rural areas, “the scientists said.
After collecting the results, the Academics modeled the system in Trnsys and the validation tricks have shown that it was ‘both reasonable and reliable’. The simulation is performed during the entire six months of the heating season and fashion 4 outperformed mode 3. Modus 4 had a COP of 4.6 and SF of 77.9%, which increased by 15.9% and 20.3% compared to mode 3. Also modus 4 used 405.2 kWh less energy 3.
“The operating costs are considerably influenced by local policy for electricity prices. Without peak valley prices, Modus 4 reduces operating costs by 28 % compared to mode 3, while the operating costs in mode 4 are only 2.6 % higher than in mode 3 with peak valley prices, ”the analysis turned out. “This suggests that optimizing operational mode can minimize operating costs according to the local policy for electricity prices. For households in the countryside, Modus 3 is the more economic option under peak valley prices, while Mode 4 offers a more sustainable solution for energy saving and emission reduction from the perspective of the national government. “
The results were presented in “Performance analysis of solar-air heat pump heating system coupled to sand-based thermal storage floor in the countryside of Binnenmongolia, China“Published in Case studies in thermal engineering. The study was conducted by researchers from Chinese Zhongyuan University of Technology and Dalian University of Technology.
This content is protected by copyright and may not be reused. If you want to work with us and reuse part of our content, please contact: editors@pv-magazine.com.
