A. Hambarian* and W. Akunyan

American University of Armenia (AUA), Engineering Research Center (ERC), 40 Marshall Baghramian,

Yerevan 0019, Armenia
Corresponding Author, arthambr@aua. am

Abstract

Being one of the early ones in the world, this is the first solar driven desiccant cooling system in Armenia and NIS. The article discusses issues related with the operation of the system since its commencement in February 2002. Topics involve: A. Efficiency issues, covering influence of the perception of humidity, quality of the windows of the space cooled, monitoring results; B. Reliability, including malfunctions related to heat recovery wheel drive, fluid (antifreeze) circulation, overheating, sediment formation on three-way valves; solar heat exchanger breakage due to ice formation; C. other operational issues: PV system integration; filters problem.

Keywords: solar hot water, solar driven cooling, desiccant cooling, solar PV.

1. Introduction

“Design And Installation of a Solar Driven Desiccant Cooling Demonstration System” (DESODEC) project funded by INCO Copernicus Program of the EU involved more than three years of collaborative work of five partners: the DER/INETI (Portugal), ISE/Fraunhofer (Germany), InterSolarCenter (Russia), Contact-A and Engineering Research Center of the American University of Armenia. As a result, with the energy provided by the Solar Water Heating (SWH) collector field installed on the rooftop of the AUA building and operation of the Desiccant Evaporative Cooling (DEC) machine, heating and cooling capability is achieved in a 154 seats auditorium of AUA.

In this article we summarize 6 years experience of the operation of the DESODEC system.

2. Description of the system

The solar field, fig. 1 consists of 32 flat plate hot water collectors with total surface area of 64 m2 providing up to 40 kW of power equivalent. The solar field and the panels are designed by DER/INETI together with Contact-A and manufactured by SolarEn LLC company in Armenia. Desiccant cooling machine comprising desiccant wheel, heat recovery wheel, humidifiers, fans and control and monitoring devices are designed by ISE/Fraunhofer and manufactured mostly in the USA and Germany. The system can deliver up to 8000 m3 cooled air with cooling power equal to 60 kW in the desiccant cooling mode to the Auditorium (fig. 2) [1-4].

The system has a 3 ton stratified storage tank designed to provide a heat buffer and a temperature difference for efficient thermodynamic cycle.

Figures 2. a. and b. describe the solar driven desiccant cooling well-known operating principle employed: air that is pre-desiccated by the desiccant absorption (evaporative cooling) wheel is cooled by humidifiers. The cooling efficiency of humidifiers is considerably elevated due to the air desiccation. Solar energy is used for regeneration of the desiccant absorption wheel. To increase the efficiency of the process, a heat recovery wheel is used to return useful energy (cold or warmth) from the exhaust channel.

Thus, in this system, a cooling or heating function is performed by a solar driven machine, that uses up to 40kWheat low potential solar energy provided by solar hot water panels, and an average of 5kWelectric, for driving the balance of the system.

3. Operation

Figures 4. A. and b. show the screenshots of the system controls interface that have comprehensive information on the operation. One can see that water temperature of 94°C is required to output 16.6°C air with relative humidity equal to 52%, and at 70.7°C yields 23.8°C and 56% respectively.

b.