Edinburgh Napier University

  The integrated collector storage (ICS) is the type of solar water heater that has retained its existance for well over a century. The flat absorber plate ICS collector type is a relatively recent addition. Being effective, low cost and simple to manufacture, their importance has been further enhanced by the recent upsurge in efforts to effectively tap renewable energy resources. Having different inclinations based on latitude, the design of flat plate heaters can benefit from extensive amount of research on the topic of natural convection in inclined cavities. More than half-century of exploration on inclined cavities has witnessed added activity particularly in the last three decades. Despite this consistent research, efforts to apply the outcomes to the flat plate collectors have been few and collectors reported in the literature appear to be deficient in embedding the knowledge into the design parameters. For an ICS type heater, natural convection studies gain even more weight as the apparatus is functionally an assembly of two natural convection cavities: an air cavity (space between the absorber and cover plates) and a water cavity (water storage tank). An extensive review of previous studies on inclined cavities relevant to flat plate collectors has been complied and discussed. Experimental tests of the ICS heater have been conducted for controlled heat flux up to 400 W. The thermal performance of the heater is recorded experimentally at angles 0–60° from horizontal, in 15° intervals. CFD analysis is also carried out for the same and is found to be in good agreement with previous studies. It was found that for any given constant value of heat flux, the performance of the heater is a strong function of the angle of inclination. The optimum configuration of the heater for Edinburgh conditions (latitude 55°55′N) is also evaluated. The present study also covers the convective behavior inside the water tank, which has been neglected in the past. A step-by-step build-up approach is adopted to resolve water tank behavior as its treatment as a simple natural convention cavity is invalid. This article would serve as a design guide for developing heaters tailored for a specific geographical location.