The performance of inclined FPSWD has been carried out by installing the system which consists of 10 panels, i.e., area of 30 m2 at the Out—Door Test Bed of Solar Energy Centre, MNRE (latitude: 28° 25′31.2′′N-longitude: 77° 9′18.8′′E) shown in Fig. 2. This system has been evaluated and observations were recorded on the basis of field data collected (period of 8–10 h) in the month of winter and summer.
The output of fresh water achieved about 5.33 l/m2 day at the radiation 5.6 kWh/m2. It is also observed that, the inlet water was 350 ppm before distillation and distilled water was found at zero ppm. In this experiment, the temperature of the hot water, cover sheet temperature were measured with thermocouples.
To simplify the performance, some assumptions and nomenclature are made in this paper.
The system is vapor leakage proof. Drunkle procedure is summarized by Tiwari et al. (2003). According to this procedure, the hourly evaporation per square meter from solar distillation is
$$Q_{\text{ew}} = 0.0163 \cdot h_{\text{cw}} (P_{\text{w}} - P_{\text{ps}} ),$$
(1)
where h
cw(kW/m2 °C) is convective heat transfer coefficient from water surface to polycarbonate sheet.
The saturation water vapor pressure (kPa) is expressed as
$$\begin{aligned}P_{\text{w}} &= 100\left( 0.004516 + 0.0007178t_{\text{w}} - 2.649\right. \\ &\qquad \left.\times 10^{ - 6} t_{\text{w}}^{2} + 6.944 \times 10^{ - 7} t_{\text{w}}^{3} \right)\end{aligned} ,$$
(2)
where t
w is temperature of water in °C.
And, the saturation water vapor pressure of polycarbonate sheet is defined
$$\begin{aligned} P_{\text{ps}} &= 100\left( 0.004516 + 0.0007178t_{\text{ps}} - 2.649 \right.\\ &\qquad \left. \times 10^{ - 6} t_{\text{ps}}^{2} + 6.944 \times 10^{ - 7} t_{\text{ps}}^{3} \right). \end{aligned}$$
(3)
The instantaneous efficiency is expressed as
$$\eta_{\text{i}} = \frac{{Q_{\text{ew}} }}{{G_{t} }},$$
(4)
where G
t
is global radiation in kWh/m2 per day.