**2. Experimental setup**

The solar chimney used in modelling drying conditions is shown in Figure 2. The experimental solar chimney is a hollow cylindrical channel of glass glazing. The walls of the chimney were made as smooth as possible to reduce pressure losses due to wall friction. The absorbing surface (collector) is a tri-wing multi-flapped selective absorber plate draped inside the glazed glass. This chimney is mounted above the room space (drying chamber) through which dry air passes.

**Figure 2.** Schematic diagram of solar chimney

Solar chimney performance analysis for natural circulation dryers reported that simple air heater increases ventilation up to some extent but not sufficiently [1]. Also, Duffie, and Beckman, (2003) experimentally analyzed an inclined window-sized roof solar chimney and found its summer performance to increase. Duffie, and Beckman, (2003) equally studied the effects of various performance parameters like chimney width and height and solar radiation on flat-plate collectors. The thermal analysis on tri-wing collectors both at steady and transient states is an entirely new area of collector configuration research with limited research out‐

For effective design of tri-wing solar chimney, solar parametric equations were utilized to model drying conditions at chimney inlet and outlet to maximize the differentials between system temperatures and air densities and their effects on drying applications. The air density depends on the temperature; hence, it also implies that the maximum differentials between the chimney air temperature and the ambient temp should give the best chimney performance.

The first mathematical model for the solar chimney design (Trombe wall) was given by [3, 16], and they also reported the concept of increasing airflow by increasing solar irradiation. This theoretical study also reported an air change per hour with change in the coefficient of fluid (air) discharge. Alter, (2011) reported the mathematical model of a conventional vertical chimney which operates under natural convention conditions where the temperature of the air inside the chimney is warmer than outside. Shiv et al., (2013) reported that solar chimney as a solar air heater may be represented by position (as vertical or horizontal chimney), or as a part of a wall (in the form of Trombe wall) or as a roof solar collector [6]. The roof solar chimney is the most convenient and mature technology used for buoyancy-driven natural

A complete analysis of the tri-wing collector with a mathematical model is cumbersome because of its distinct features compared to an ordinary flat-plate model comparison of its performance effectiveness with experimental design data using high-precision apparatus and equipment offers a realistic solution. The objective of this study is to use analytical method to derive expressions for modelling drying effects of buoyant airflow created by solar heating of

The solar chimney used in modelling drying conditions is shown in Figure 2. The experimental solar chimney is a hollow cylindrical channel of glass glazing. The walls of the chimney were made as smooth as possible to reduce pressure losses due to wall friction. The absorbing surface (collector) is a tri-wing multi-flapped selective absorber plate draped inside the glazed glass. This chimney is mounted above the room space (drying chamber) through which dry

comes.

**1.1. Project objective**

28 Solar Radiation Applications

ventilation systems [7, 8, 9].

a tri-wing collector.

air passes.

**2. Experimental setup**

#### **3. Solar incident radiation on each wing**

The incident angle of radiation reaching any collector surface is expressed by the general expression

$$\text{Cost } \theta = -\sin\delta\cos\rho\cos\chi + \cos\delta\sin\rho\cos\chi\cos\rho + \cos\delta\sin\chi\sin\rho \tag{1}$$

This expression was used to model the following equations for each of the wings in terms of ω as

$$\text{Cost } \theta = -\left(0.1761 + 0.053 \cos \alpha + 0.81 \sin \alpha\right) \text{ for wing1} \tag{2}$$

$$\text{Cost } \theta = -\left(0.353 + 0.1106 \cos \alpha\right) \text{ for wing 2} \tag{3}$$

$$\text{Cost } \theta = -\left(0.1764 - 0.053 \cos \alpha - 1764 - 0.0 \alpha\right) \text{ for wing } \mathbf{3} \tag{4}$$

Previously the expression for all the wings has been derived as

$$0.\text{Cost}\_x = 0.9288\text{Cost} - .9288\tag{5}$$
