Solar Heat for Materials Processing: A Review on Recent Achievements and a Prospect on Future Trends

Abstract

Considering works published in the literature for more than a decade (period from January 2008 till June 2019), this paper provides an overview of recent applications of the so-called “solar furnaces”, their reactors, process chambers and related devices, aiming specifically at the processing of (solid) materials. Based on the author’s own experience, some prospects on future trends are also presented. The aim of this work is to demonstrate the tremendous potentialities of the usage of solar heat for materials processing, but also to reveal the necessity of further developing solar-driven high-temperature technologies (which are required to displace the use of electricity or natural gas). In particular, it is essential to improve the temperature homogeneity conditions inside reaction chambers for materials processing using solar heat. Moreover, new innovative modular systems, practical and flexible, for capture, concentration, control and conduction of concentrated solar radiation are suggested. Solar thermal technologies for the production of electricity, as well as solar thermochemical processes for production of gases or liquids, are outside the scope of this review.

Titanium solar metallurgy – Earth and Space

“…After establishing of the Earth industry for solar metallurgy [10] of titanium the basic knowledge will be obtained for future Space application of concentrated solar power on Moon, Mars and in main asteroid belt.…”

“…This temperature is sufficient for melting of almost all types of materials. Recent experimental works [3][4][5][6][7][8][9][10] proved that the concentrated solar energy can be successfully used in the solar powder metallurgy of titanium, porous titanium, titanium alloys, surface treatment of titanium and compounds and even for welding of Ti6Al4V titanium alloy. Titanium foams were sintered by García et al [3] in argon using NaCl as soluble spacer.…”

“…From industrial point of view it can be efficiently applied at countries of Earth solar belt with adequate resources of titanium ores. Unfortunately, the solar titanium industry is not developed yet [10]. Therefore King Fahd University of Petroleum & Minerals, Saudi Arabia, in cooperation with IMMM and IVMA STU, Slovakia started works on creation of industrial equipments for solar powder metallurgy of titanium.…”

Computer Modelling of the Optical Behavior of Homogenizers in High-Flux Solar Furnaces

“…In high-flux solar concentration systems, the flux of solar radiation that reaches the target is non-homogeneous, as discussed in our previous modelling work [1,2] and illustrated by considerable experimental evidence. Therefore, to expand the application field of solar-driven high-temperature technologies it is essential to improve the temperature homogeneity conditions, because for many applications, it is important to obtain a radiation distribution as homogeneous as possible over the working area [3]. For processing of (solid) bulk materials at the industrial scale (e.g., firing of ceramics, heat treatment of metallic parts, furnaces for glass melting or for glass fritting, calcination furnaces, etc.)…”

“…Until now, almost all the so-called "solar furnaces" are point-focusing solar concentration facilities. These high-flux solar furnaces are located throughout the world at universities, research institutes, and companies, operating at concentrations relevant to solar thermochemistry, materials processing, and thermal treatments [3]. Figure 1 shows a typical diagram of a typical high-flux solar furnace.…”