Heating and Cooling with a Small Scale Solar Driven Adsorption. Chiller Combined with a Borehole System

Dr. Tomas Nunez*; Bjorn Nienborg; York Tiedtke

Fraunhofer-Institut for Solar Energy Systems ISE, Heidenhofstrafte 2, 79106 Freiburg, Germany
* Corresponding Author, tomas. nunez@ise. fraunhofer. de

Abstract

The performance of a solar driven adsorption cooling system is presented in this paper. The system consists of a reversible 5.5kW adsorption machine from the German company SorTech, a 20m2 flat plate collector field with a 2m3 buffer storage and a borehole array of three 80m boreholes. In the summer period, the adsorption machine is operated as a chiller driven by solar energy while the boreholes are used for heat rejection. In winter it is operated as a heat pump driven by the heat from a heating network and using the boreholes as low temperature heat source. The operation results presented here correspond to the period from June 4th to December 1st, 2007. The machine as well as the whole system operated reliably and as expected during the whole monitoring period. An overall thermal COP of 0.57 and an hourly mean chilling power of around 4.4kW were obtained during the cooling season. The electricity consumption was about 10% of the produced cold. During the heating season a thermal COP of 1.43 and hourly mean heating powers of 9.4kW were obtained. Frequency distributions of the registered driving, heat rejection and chilled water temperatures give a picture of operation conditions in a real application.

Keywords: adsorption, solar cooling, ground source heat exchanger, system performance

1. Introduction

In the frame of the finished EU project MODESTORE a solar driven cooling system with a 5.5kW reversible adsorption chiller was installed at the Fraunhofer Institute for Solar Energy Systems. In a previous publication [1] first simulation results which resulted in the present design and dimensioning of the system were published. In this publication the system performance and operation results from the first operation period in both modes (cooling and heating) is presented.

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