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A numerical method is proposed to calculate earth-energy of earth-air-pipe heat exchanger during winter heating. The proposed method is based on using numerical computation developed on Scilab a free open source software. Authors showed the comparison between their simple numerical model called Heatground with the well-known Amitrano results. The comparison is given for different parameters as the airflow, the pipe length, the depth of buried pipe, the pipe diameter.

$EVWUDFW 7KH DXWKRUV SUHVHQW D PHWKRG RI GHWHUPLQDWLRQ RI WKH SDUDPHWHUV RI WKH PRGHO GLRGHThe majority of simulations of the working point of the PV module are obtained from the electrical equivalent circuit shown in figure n°3. The knowledge of the electrical parameters is essential to predetermine the behaviour of the panels subjected to various irradiation and temperature. However, the manufacturers only give the external PV characteristics and give less information about these parameters. The authors present a simplified graphical method of determination of these parameters. The manufacturing processes induce disparity in the I-V characteristic. This fact it is possible to find an optimal association of PV modules. However, the expression of the power is implicit and can be only obtained by numerical resolution [1] or iterative. So, it is quite difficult to establish the rules of association of PV modules. The authors show that an approximate analytical expression of the maximum power can be deduced from the equivalent electrical circuit. The expression introduces two remarkable factors such as the open circuit voltage (V OC ) and the short-circuit current (I SC ) and also correction factors in order to take into account the various imperfections of the solar cells. (TXLYDOHQW HOHFWULFDO FLUFXLW RI WKH 39 PRGXOHA PV module is an association made of N S photodiodes connected in series to increase the output voltage and N P identical node to increase the available delivered electrical power.

A new expression is proposed to calculate the earth-energy of an earth-air-pipe heat exchanger during winter heating for three kinds of soil in France. An analytical model is obtained by using numerical computation developed in Scilab -a free open source software. The authors showed the comparison between their simple analytical model and experimental results. They showed the influence of different parameters to specify the size of the heat exchanger.

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