Methodology for Determining the Efficiency of a Solar Air Heater with an Air-Permeable Matrix Absorber Made of Tangled Metal Wire
Abstract
An improved design of a solar air heater with an air-permeable matrix absorber made of tangled metal wire is developed as a utility model. A thermal model is proposed for this design of a matrix solar air heater with allowance for its geometric, thermophysical, optical, and operating parameters. To simplify the problem, it is assumed that the air-permeable matrix absorber made of tangled metal wire is a porous material with a thickness δ, a porosity of the absorber p, and a constant thermal conductivity coefficient of the solid skeleton $${{{{\lambda }}}_{{\text{c}}}}.$$ Based on the adopted thermal model, a method is developed for determining the thermal efficiency coefficient $$F{\kern 1pt} '$$ of the solar air heater and its total heat loss coefficient UL. An example calculation for the developed improved design of a solar air heater with an air-permeable matrix absorber made of tangled metal wire is provided. It demonstrates in steps the method and source for determining the coefficients included in the dependencies for calculating the efficiency coefficient $$F{\kern 1pt} '$$ and the total heat loss coefficient UL.