Docent Vlasova I, Kovalyov A.

Donetsk National University of Economics and Trade named after

M. Tugan-Baranovsky

SOLAR REFRIGERATING AND AIR CONDITIONING

(dehumidification & EVAPORATING) SYSTEMS.

INTERNATIONAL RESEARCHES IN THE FIELD

Aggravating interconnected problems of energy and ecology set up new requirements for the comfort and technology of air conditioning and refrigerating systems. This concerns the reduction of energy consumption and the anthropogenic impact on the environment. Creation of alternative systems based on non-conventional energy sources and evaporation cooling and wet-thermal treatment of cooling mediums is one of the most perspective solutions in this area.

The wide practical application of evaporation methods in current solar heating and cooling systems requires enlargement of climatic application area of these methods, increase of compactness and reduction of power consumption of heat mass exchange apparatuses which are parts of such systems.

The development of high-efficient solar collectors (SC) and indirect evaporative coolers (IEC), in which the air flow is cooled without direct contact with water, is of special interest. Evaporative cooling is efficient in dry and hot climate (where х_g < 12-14 g/kg). The most perspective is an application of evaporative coolers in the solar systems (dehumidification evaporating systems), something that makes it possible to eliminate climatic restrictions of application of the evaporative methods and considerably improve energy efficiency and ecological indices of the alternative systems in general. The most perspective for creation of alternative solar systems is an open absorption cycle using liquid sorbents and solar energy for sorbent regeneration. Alternative solar air conditioning systems are especially promising, something that is conditioned by a certain correlation between the insolation and required cooling level and comparatively low temperatures of absorbent regeneration.

Among the key problems of development of alternative solar systems, which should be solved to let them enter the market, are: development of new circuit solutions and improvement of design of solar collectors and indirect evaporative coolers; creation of compact heat mass exchange apparatuses standardized for all basic elements, consuming minimum energy for heat medium circulation and highly compact in sizes; wide application of polymeric materials in heat mass exchange apparatuses; complex theoretical and experimental study, discovering dependences and recommendations for calculation and engineering application in the field of creation of alternative systems; environmental assessment of new solutions; creation of combined systems of autonomous heat supply, refrigeration and air conditioning, i.e. life support systems flexible enough and easily controlled.

The new generation of solar drainage and evaporating cooling refrigeratory and conditioning systems (system solutions and the bases of designing) on the basis of absorbent cycle of atmosphere or low pressure (absorbent cycles of open and mixed types) with compulsory (partial) use of solar energy for absorbent regeneration has been developed. In the recent years such systems have attracted interest in the world science and practice being the most perspective alternative means of traditional vapor compression systems. Preliminary drainage of airflow makes it possible to use evaporating process for cooling irrelative of the parameters of the environment and achieve deep cooling. System solutions provide noncontact (in respect of absorbent solution) treatment of airflow getting into the premises (in АСКВ systems) or providing cooled water inside (in the system of aero-air heat exchangers).

Modern heat mass exchanging apparatus TMA for alternative systems (solar collectors, absorber-dehydrator, stripper-regenerator, evaporative coolers of direct and indirect types) on the bases of polymeric multi-channel structures has been developed within the framework of this subject. At the heart of TMA the results of longstanding investigations of the authors in the sphere of development and creation of a compact apparatus of membranous type have been put. Decrease of size and power inputs for personal needs of an alternative system are reached by means of TMA creation with combining several operating processes in each of the apparatus, for instance absorber-dehydrator with inner evaporating cooling which allows to approximate the process of absorbtion to isothermal. All the TMA which are the part of АСКВ are unified; regulatory roughness of work surface is used as a method of intensification.

The scientific bases (thermodynamic analysis, heat-mass exchange in processes of absorption, desorption and evaporative cooling, aerohydrodynamics) and the designing bases of heat-mass exchanging apparatus (on the basis of multi-channel and multi-layer adapter structures from polymeric materials with interchange of channels for realization of operating and auxiliary processes: air drainage in absorber, regeneration of absorber in stripper, evaporative cooling in refrigerants of direct and indirect types) have been developed. The selection and the analysis of thermalphysic features of operating substances – composites taking into account the required cooling level, work on a heating source and impacts on structural materials have been conducted; the analysis of configuration and composition of a heating source (under the obligatory fractional constituent of solar energy) has been made.