*2.2.1 Experimental setup*

Double-slope solar still shown schematically in **Figure 5** was used to conduct the experiments [21]. Concerning **Figures 1** and **2**, we have designed this schematic

### **Figure 3.**

*Classes of materials that can be used as PCM and their typical range of melting temperature and melting enthalpy [15].*

**Figure 4.** *Various materials used for solar distillation [3].*

**Figure 5.** *Schematic of double-slope solar still measurements in cm.*

with lines of varying strokes and measurements of solar still that we implemented for real-time experiments.

As shown in **Figure 5**, the base or basin of double-slope solar still was made using an 18-mm-thick waterproof plywood obtained from a local vendor marking the instance of the in situ experimental setup. The side walls were constructed using the same 6-mm thick plywood. The solar basin had an approximate active area (A) of 0.9 m<sup>2</sup> . The inside of still was coated with waterproofing M-Seal an epoxy compound with a resin and a hardener. The compound prevents leakage through joints of sidewalls and the base of the still [22].

Since solar radiation has three components for the receiving surface namely, absorption, reflection, or transmission.

**175**

*Water Desalination Using PCM to Store Solar Energy DOI: http://dx.doi.org/10.5772/intechopen.92597*

We see, from conservation of energy:

of ±0.2°C and a least count of 0.1°C [23–25].

/day.

**τ = 0, so that: α + ρ = 1**

with black,

area (*A*) of 0.9 m<sup>2</sup>

(*E*) is 5.44 kWh/m2

*on a bright sunny day*.

4.895) or 440.55 kWh.

mum space needed is 13 m<sup>2</sup>

*2.2.2 Solar distillation without PCM*

0.07 m and calculated relevant parameters [20].

To account for these characteristics, we introduce additional properties:

• Absorptivity, **α**, as the fraction of incident radiation absorbed.

• Transmissivity, **τ**, the fraction of incident radiation transmitted.

**+ + = 1** (3)

The basin of the still was also painted black. Owning the height (*h*) of 0.2 m and

*V = h × A* (4)

0.900 *×* 0.2 *=* 0.0180 **m<sup>3</sup>** *or* 180 **L**

Through the sidewalls, the distillate was collected via streamline channels. In an enclosed basin tank that was subjected to the solar radiation was filled with tap water via the inlet valve. Temperatures of water, glass cover, and water-vapor mixture were noted every hour using thermocouples of k-type, which have an accuracy

Distillate collected was also measured during temperature recording. Solar intensity falling on solar still was taken from the reading measured by Pyranometer. We had statistical knowledge from SynergyEnvio-Engineerings that around Udupi, Karnataka (*Latitude: 13.35, Longitude: 74.75*). Annual average of solar irradiation

*With an area of* 0. *9m*<sup>2</sup> *translates to* **A ∗ E = 5.44 ∗ 0.9 = 4.895 kWh/day**

For approximately 90 bright sunny days in summer, this translates to (90 ×

Water was the sole element in the still influencing the heat released and the rate of interphase mass transfer. So we studied the water up to two depths 0.05 and

The PCM material was evenly distributed and covered by a 5-mm thick metal plate. The sides of the metal plate were sealed using M-Seal chemical to avoid leakage or contact of PCM and water. The same solar distillation experiments were conducted with a fixed amount of different PCM, and the distillate collected was

*2.2.3 Experimental investigation to find the effect of PCM on solar distillation*

440.55 kWh energy per still, considering a rooftop has room for 10 stills (maxi-

), this energy is equivalent to *4405.5 kWh* [18].

Since the solar still includes opaque surfaces, as we are painted the walls

• Reflectivity, **ρ**, the fraction of incident radiation reflected.

basin has the capacity of

*Thermodynamics and Energy Engineering*

*Various materials used for solar distillation [3].*

**174**

(A) of 0.9 m<sup>2</sup>

**Figure 5.**

**Figure 4.**

for real-time experiments.

joints of sidewalls and the base of the still [22].

*Schematic of double-slope solar still measurements in cm.*

absorption, reflection, or transmission.

with lines of varying strokes and measurements of solar still that we implemented

As shown in **Figure 5**, the base or basin of double-slope solar still was made using an 18-mm-thick waterproof plywood obtained from a local vendor marking the instance of the in situ experimental setup. The side walls were constructed using the same 6-mm thick plywood. The solar basin had an approximate active area

compound with a resin and a hardener. The compound prevents leakage through

Since solar radiation has three components for the receiving surface namely,

. The inside of still was coated with waterproofing M-Seal an epoxy

To account for these characteristics, we introduce additional properties:


We see, from conservation of energy:

$$
\mathfrak{a} \star \mathfrak{p} \star \mathfrak{r} = \mathbf{1} \tag{3}
$$

Since the solar still includes opaque surfaces, as we are painted the walls with black,

**τ = 0, so that: α + ρ = 1**

The basin of the still was also painted black. Owning the height (*h*) of 0.2 m and area (*A*) of 0.9 m<sup>2</sup> basin has the capacity of

$$\mathbf{V} = \mathbf{h} \times \mathbf{A} \tag{4}$$

$$0.900 \times 0.2 = 0.0180 \text{ m}^3 \text{ or } 180 \text{ L}$$

Through the sidewalls, the distillate was collected via streamline channels. In an enclosed basin tank that was subjected to the solar radiation was filled with tap water via the inlet valve. Temperatures of water, glass cover, and water-vapor mixture were noted every hour using thermocouples of k-type, which have an accuracy of ±0.2°C and a least count of 0.1°C [23–25].

Distillate collected was also measured during temperature recording. Solar intensity falling on solar still was taken from the reading measured by Pyranometer. We had statistical knowledge from SynergyEnvio-Engineerings that around Udupi, Karnataka (*Latitude: 13.35, Longitude: 74.75*). Annual average of solar irradiation (*E*) is 5.44 kWh/m2 /day.

*With an area of* 0. *9m*<sup>2</sup> *translates to* **A ∗ E = 5.44 ∗ 0.9 = 4.895 kWh/day** *on a bright sunny day*.

For approximately 90 bright sunny days in summer, this translates to (90 × 4.895) or 440.55 kWh.

440.55 kWh energy per still, considering a rooftop has room for 10 stills (maximum space needed is 13 m<sup>2</sup> ), this energy is equivalent to *4405.5 kWh* [18].
