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Indian researchers have combined photovoltaic generation with heat produced by a ground-to-air heat exchanger to heat and cool buildings. They state that the proposed system could result in an annual energy gain of 8,116.7 kWh.
Researchers at the Central University of Jharkhand in India have developed a thermal energy system for buildings that uses a ground-air heat exchanger (EAHE) system powered by a stand-alone photovoltaic system.
An EAHE is a passive geothermal solution consisting of a system of buried pipes through which fresh air circulates. These systems are commonly used to heat the cool air in buildings in winter and cool it in summer.
“In a nutshell, the EAHE is based on the concept of using temperatures below 2-3 m of the earths surface that remain constant throughout the year, regardless of ambient air temperature variations,” he explains to pv magazine . researcher Basudev Pradhan. “The temperature below the Earths surface is colder in summer and warmer in winter than the air above it. Therefore, the designed system will blow ambient air through a pipe installed at a certain depth from the surface, and the air will be heated or cooled in winter or summer due to heat exchange with the surrounding soil.”
Scientists designed the proposed PV EAHE with a statistical tool response surface approach, using calculation and modeling software. The EAHE is designed with PVC pipes inclined at a slight angle to prevent condensed water from stagnating inside and buried horizontally. The solar array consists of photovoltaic panels, charge regulators, an inverter and a battery.
The researchers assumed that the EAHE would operate for 24 hours every month except July and August. They indicated that the seasonal energy efficiency ratio (SEER) is estimated at 7.34 for cooling and 8.99 for heating. They also calculated the annual heating and cooling potential of the system to be 4,158 kWh/year and 3,958.7 kWh/year, respectively.
"Thus, from the information revealed, it can be concluded that, in winter, the designed EAHE system works more efficiently than in summer," they explained.
They pointed out that the configuration designed with optimized parameters results in an annual energy gain of 8,116.7 kWh.
“If grid electricity is available 24 hours a day, the solar system has a direct payback period of four to five years,” the researchers noted. “In addition, this hybrid system has the potential to provide carbon credits worth 336.86 kWh/year. Therefore, this system is an energy-saving and environment-friendly approach both for urban areas with 24-hour network availability and for rural areas where network extension is not possible or feasible due to some technical barriers.”
They presented the system in the article “ Numerical simulation of stand-alone photovoltaic integrated with earth to air heat exchanger for space heating/cooling of a residential building ”. heating/cooling of a residential building), recently published in Renewable Energy.
“These zero net efficiency stand-alone systems can be optimized for different locations and climate conditions based on varying atmospheric and ground parameters,” Pradhan explains. |
