ENGINEERING FOR RURAL DEVELOPMENT Jelgava, 24.-25.05.2012. 527 NEW INVESTIGATIONS IN SOLAR AIR HEATING COLLECTORS Guntis Ruskis, Aivars Aboltins, Janis Palabinskis Latvia University of Agriculture guntisruskis@inbox.lv, aivars.aboltins@inbox.lv, janis.palabinskis@llu.lv Abstract. The objective is to create and explore the easy-folding, disrupting, easily portable air heating solar collectors, which can be inflated and disassembled as many times as needed. The solar collector has to be constructively simple and cheap as well as simple and easy to transport. That could be an inflatable air heating solar collector. The inflatable base could be a good insulator on the one hand and absorbent on the other hand. We need to find out the air-heating collector efficiency. The study results confirm that the manufactured solar collector is sufficiently effective and easy to produce with small financial contributions. The average ambient air temperature increase in the experiments is 10.2 ºC and max increase is up to 16 ºC. This collector gives good correlation with the air heating degree and radiation (r = 0.93) and the efficiency coefficient of this collector is  = 0.63. Comparing the efficiency of the collector manufactured with another coating and the absorbent material collectors shows that the collector is manufactured for use in air heating. Keywords: solar energy, air heating, inflatable collector. Introduction In recent years, increasing attention in the world is being paid to renewable energy resources in the economy, which have replaced the use of fossil fuels, which contribute to economics (oil, gas, coal prices) affecting the environment (the most common greenhouse gas emissions that cause greenhouse emergence), as well as safety (in 2011 the events in Japan, where the earthquake and tsunami caused nuclear disasters) factors. The sun, that alternative energy source, more and more widely is used in national economics. The greatest advantage of solar energy as compared with other forms of energy is that it is clean and can be supplied without environmental pollution. So, if more people use solar energy to heat the air and water in their homes, our environment would be cleaner. Solar air heating is a solar thermal technology in which the energy from the sun, solar insolation, is captured by an absorbing medium and used to heat air. Solar air heating is a renewable energy heating technology used to heat or condition air for buildings or processes of heat applications. It is typically the most cost-effective out of all the solar technologies, especially in commercial and industrial applications, and it addresses the largest usage of building energy in heating climates, which is space heating and industrial process heating. Increase in the energy prices is an urgent problem in Latvia, so solar energy can be a good alternative to reduce the dependence on the fossil resources supplier countries. We can use solar energy to heat and cool buildings (both actively and passively), dry products, heat water for domestic and industry use, heat swimming pools, generate electricity, for chemistry applications and many more operations. In general, solar air heaters are flat-plate collectors (FPCs), consisting of an absorber, a transparent cover, and backward insulation. The performance of solar air heaters is mainly influenced by the meteorological parameters (direct and diffuse radiation, ambient temperature and wind speed), design parameters (type of collector, collector materials) and flow parameters (air flow rate, mode of flow). The principal requirements of these designs are a large contact area between the absorbing surface and air [1]. The air heating collectors can be used in two main directions for product drying and room heating (ventilation). Product issues through drying in sun-warmed air are discussed in a lot of works [2; 3]. We are exploring a variety of coating and absorbent materials to increase the air warm-up stage. There are different efficiency solar air heating collectors, it depends on the collector cover materials (polyvinylchloride film, cell polycarbonate PC, translucent roofing slate), absorber (black collared wood, steel-thin plate etc.) and insulation of the collector body with different air velocities in the collector; it was investigated in our works [4 – 8]. Mostly a lot of research is done for flat-plate solar collectors, these collectors are very big, we tried to create easy-to-use and easy for storage conditions, the collector that would take little space, and we had the idea of an inflatable collector. We