**Steady State Thermal Analysis of a Tri-Wing Solar Chimney**

R. S. Bello, C. N. Ezebuilo, T. A. Adegbulugbe and K. A. Eke

Additional information is available at the end of the chapter

http://dx.doi.org/10.5772/59721

#### **1. Introduction**

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26 Solar Radiation Applications

The solar chimney is one of the technologies which work on the principle of buoyancy, in which air is heated through the greenhouse effect generated by solar radiation (heat energy) at low cost. The solar chimney is a passive solar ventilation system (non-mechanical) that can be installed on roofs or in walls. The heat is transferred based on the convective cooling principle which works on the fact that hot air rises upward; these chimneys reduce unwanted heat during the day by displacing interior (warm) air with exterior (cool) air. Solar chimneys are mainly made of a black, hollow thermal mass with an opening at the top as an exit for the hot air. The air in the room exits from the top of the chimney (Figure 1). The process can also be reversed for room heating.

**Figure 1.** Solar chimney [1]

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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‐ comes.

#### **1.1. Project objective**

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 ventilation systems [7, 8, 9].

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 a tri-wing collector.
