L. Bujedo1*, J. Rodriguez2, P. J. Martfcnez3, L. R. Rodriguez4 and J. Vicente1

1 CARTIF, Parque Tecnologico de Boecillo Parc 205, 47151 Boecillo, Spain
2 Institute for Renewable Energy, EURAC Research. Viale Druso 1, 39100 Bozen/Bolzano. Italy
3 Miguel Hernandez University, Av. De la Universidad s/n, 03202 Elche Spain
4 University of Burgos, E. Politecnica Superior Ed. La Milanera, C/ Villadiego, s/n,. 09001 Burgos (Spain)

* Corresponding Author, luibuj@cartif. es

Abstract

The present work has the aim to evaluate in a qualitative and quantitative way the influence, on the performance of the solar cooling installations, of two fundamental aspects: the hydraulic configuration and the implemented control. In order to do that they has been established three basic configurations and six control strategies for each one of them. The three first control actions act on the solar part and the other three on the thermal chiller, and so there are 18 simulations carried out on the simulation environment TRNSYS. Thanks to that they have been evaluated and compared the most important parameters: solar production, solar fraction, COP etc. As can be seen, the results have shown important variations on the obtained data. Different control actions applied to the solar part have repercussions on the performance of the chiller and vice versa, different control systems for the chiller, produce changes on the working conditions of the solar installation. Besides there can be seen how the most adequate control for the solar installation is the one with flow variation, combined with start up by critical radiation. The control for the chiller that better results gives is the one based on variable flow with pump. The cold storage produces a reduction of the performance of the installation, but from the point of view of design, allows having an absorption chiller of smaller size.

Keywords: solar cooling, control, hydraulic configuration, performance.

1. Introduction

During the years 2003 to 2006, it was carried out the project “Optimization de los Procesos de Refrigeration Solar” (Solar Cooling Processes Optimization) by the Research Centre CARTIF in association with the Universities of Burgos and Miguel Hernandez from Elche. This project called ORESOL was financed by the Education and Science Ministry of Spain (with CICYT funds).

One of the main goals of this project was to analyze and evaluate the effect of the control strategies on the solar cooling installations. In order to do that, it was considered that the most suitable way was the execution of simulations with different configurations and control strategies allowing the comparison of the results and the quantitative assessment of each one of them. They were proposed three basic hydraulic configurations: direct use installation, total use installation and installation with cold storage. Six different control strategies were applied on each one of them.

In this way, apart from evaluating the level of interaction that have the actions carried out over each part of the installation, it’s evaluated the quantitative effect.