Numerical and Experimental ......(24)

Numerical and Experimental Investigation of Building-Integrated Photovoltaic-Thermal Systems绿色建筑博客]4j"rk!K{6E'HG`

 NUMERICAL MODELING OF BIPV SYSTEM

3.3 Initial Values and Boundary Conditions

Since this problem is quasi-steady, the initial values are not important for the final results. The initial values of the flow parameters and boundary conditions are specified to begin the computer process. The initial values of temperature and velocities are set equal to the ambient conditions. The turbulent kinetic energy k and turbulent energy dissipation rate ε are set to
5q r{3AjIG0constant 1 by default. The boundary conditions are specified to simulate real conditions as follows:
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8?!S$xf H5H0(1) Outlet boundary conditions:
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Pressure-outlet, P=0
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(2) Inlet boundary conditions:绿色建筑博客0AF%V
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Pressure-inlet, T=0ºC, P=Pin (range 0.3 Pa to 2.0 Pa)绿色建筑博客JeXZ Is"E

(3) PV panel inner surface boundary conditions:
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U=0, V=0, T(h)=Tpv(h) from experiment (function of height according to experimental data regression)绿色建筑博客+r,S+`I n KV9@#r

(4)Other boundary conditions:
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U=0, V=0, Adiabatic Surface绿色建筑博客 [
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All the boundary surfaces have been assumed to be gray-diffuse with emissivity equal to 0.9 and this value is confirmed by measurements with an emissionmeter. The pressure difference between inlet and outlet is set to 0.5 Pa according to flow pressure loss calculation for the average velocity equal to 0.5m/s (measured). Different pressures are also considered to study the flow dynamics and thermal behavīor under different air velocities. The Reynolds number for the present case is calculated to be between 103 and 104 and the Rayleigh number is in the range 107 to 108. The Rayleigh number also depends on the boundary input of the PV panel temperatures. One example of the temperature inputs for the PV panel is from experimental data for February 18th, 2004, shown in Figure 3.2. It can be changed for different cases.绿色建筑博客RZD^N#m*pn\