Edo Wiemken, Alexander Morgenstern

Fraunhofer Institute for Solar Energy Systems (ISE), Heidenhofstrafle 2, 79110 Freiburg

edo. wiemken@ise. fraunhofer. de

Abstract

The federal Programme SOLARTHERMIE 2000plus, launched by the German Federal Ministry for the Environment, Nature Conservation and Nuclear Safety, provides funds for solar thermally assisted pilot and demonstration applications with collector areas of usually above 100 m2 The fields of application include solar cooling and air-conditioning as well; in this application field, Fraunhofer ISE is performing accompanying research for demonstration plants. This contribution provides brief information on the status of solar cooling within Solarthermie 2000plus and on three installations already in operation or being installed in late summer 2008 respectively; covering the wide capacity range from 40 m2 collector area in a small size system with 10 kW chiller capacity up to 1218 m2 collector area for thermal support of a 1 MW chilling capacity plant. These first three installations will use pure water as collector fluid in combination with vacuum tube collectors.

Keywords: EuroSun 2008, Solarthermie 2000plus, solar cooling, solar air-conditioning

1. Introduction

The interest in solar thermally driven cooling and air-conditioning is rising, since it allows for a de­crease in the use of primary energy for cooling and for an optimised utilisation of the solar thermal collector system. A description of the technologies is given e. g. in [1], [2]. [3]. Although the realised plants in generally have demonstrated the feasibility and functionality, some of them have also pointed to shortcomings, obstructing a braod dissemination of solar cooling so far. These obstructions are related to economic issues and to an adequate know-how in planning and installation.

To overcome the shortcomings from the past and to assess the application potential of new concepts, different projects were established on an international and national level. Examples on international projects are listed in [4]. On base cost figures from systems installed some years ago, the cost situation and the market opportunity for solar cooling was analysed within the project ROCOCO, supported by the European Commission [5]. However, in the recent years the market situation has changed, since thermally driven chillers in the small capacity range (< 20 kW chilling capacity) have entered the mar­ket or are close to market introduction [6], applicable with solar thermal heat production. This develop­ment has considerably extended the application field of solar cooling.

On a national level, the demonstration of system technology is a central objective of the programme Solarthermie 2000plus [7], launched by the German Federal Ministry for the Environment, Nature Conservation and Nuclear Safety. The programme provides funds for solar thermally assisted pilot and

demonstration applications with collector areas of usually above 100 m2, the funding of smaller applications is subject on the system concept. Areas of application are heating support, district heating support, process heating and solar cooling and air-conditioning. For the latter field of application, Fraunhofer ISE is responsible for accompanying research of the demonstration plants in this funding scheme. The accompanying research comprises mainly the areas

— Decision support to the Project Management Organisation Jtilich (PtJ) in the selection phase of the proposals in order to ensure a high quality of the installations and to estimate the environmental benefits of the systems;

— Support in the project pre-planning phase: possible improvements in the hydraulic scheme and in the integration of the cooling system and of the solar thermal system into the overall system;

— Evaluation of the monitored system data to assess the energetic performance and to identify weak points in the system control and to allow a comparative assessment of the installed plants;

— Dissemination activities;

— Participation at Task 38 Solar Air-Conditioning and Refrigeration of the Solar Heating and Cooling Programme (SHC) of the IEA.

Figure 1 provides a general overview of the organisation structure of Solarthermie 2000plus, and fi­gure 2 shows the activities within the accompanying research for solar cooling demonstration plants.