Development of new bio-compatible heat fluids, for thermal solar energy of low and medium temperature

The general objective is the development of heat bearer fluids with adequate work ranges for use in systems for production of thermal solar energy of low and medium temperature.

On the 19th of January 2007, the Spanish Government legislated a set of rules known as the REAL DECRETO 47/2007 (from now on rule 47/2007) by which solar energy for Domestic Hot Water (DHW) must be implemented in buildings of new construction. Rule 47/2007 is set to comply initially with 'The White Paper' on energy (Document COM (97) final, Brussels, 1997) from the EUROPEAN COMMISSION and finally with directive 2002/91/CE which regulates all the aspects concerning DHW and ensures maximum energy efficiency in buildings of new construction. The ultimate target is to comply with the Kyoto Protocol and reduce CO2 emissions. The general objective of the current project is the development of heat transfer fluids with adequate working ranges for its use in domestic systems fuelled by low to medium intensity thermal solar energy. In particular, this relates to application to the generation of DHW and/or domestic heating, as well as in mix cooling systems such as domestic air conditioning. All these objectives, within SPAIN, have been translated into the practical application in a new Technical Building Code entitled 'Codigo Tecnico (CT)'. This CT embraces, among others, all the technical and engineering aspects associated with efficient energy management in any type of building. Probably the most important section of the CT is the one associated with the installation of systems oriented to DHW and known as RITE (acronyms in Spanish of Regulation for Thermal Installations in Buildings). This section, although still under development, defines all parts and components to be assembled in a DHW system of any dimension i.e. from simple family houses to hotels. According to the description of the RITE, the systems that conform to the thermal solar installation are the following: * An energy collecting system formed by solar collectors. These solar collectors transform the incoming solar radiation into thermal energy. This process is accomplished by direct heating of a working fluid in close contact with the collector panel. * A system for water accumulation, constituted by one or various deposits that store the water until it is needed. * A hydraulic circuit, constituted by pipelines, bombs, valves, etc. This hydraulic circuit drives the movement of the warm fluid upstream to the accumulation system. A heat exchanger, which transfers the captured thermal energy from the working fluid to the final water contained in the accumulator. * A regulation and control system, which is in charge of securing the correct functioning of the equipment to provide the maximum amount of thermal solar energy as well as to provide protection against multiple factors such as overheating of the system, freezing risks, etc. Additionally an electrically fuelled subsystem is present. This system complements the solar contribution to cover the forecasted demand, guaranteeing the continuity of the supply of warm water in cases of scarce solar radiation. The heat transfer from the collectors to the water in the system is done by means of heat transfer fluids. These fluids must secure the correct functioning of the equipment to ensure thermal efficiency and avoid undesired effects mainly caused by scale and low temperatures. Traditionally, the heat transfer fluids working at medium temperature have been based on mixtures of diverse organic materials, including CFC, CFC and 'glycols'. Glycols are petroleum derivatives that show, to a certain extent, problems of toxicity and recycling, and are incompatible with the reduction of the green-house effect. With the implementation of the RITE, which will extend the use of DHW systems to almost any household, and due to the potential toxicity of glycols, the need to develop new working fluids of low toxicity is evident. The CT, in its section 3.2.2 on solar energy installations, states that: The basic objective of the solar system is to supply the user with an installation that: a) Optimises global energy savings in combination with the rest of the thermal equipment of the buildings. b) Guarantees sufficient durability and quality. c) Guarantees a secure use of the installation. The general objectives of the current project are the formulation of additives to prepare new heat transfer fluids of innocuous and biodegradable composition. Such additives will have straight applicability to the thermal solar energy systems of low and medium energy for domestic use, according to the RITE norm. We intend to provide heat transfer fluids with the following properties: - High ecological value - Biodegradability - Low or non existent toxicity - Ease of leakage detection - Suitable for hard water - Long durability. Keywords: Heat transfer fluids, green chemistry, domestic hot water.
Project ID: 
4 118
Start date: 
Project Duration: 
Project costs: 
460 000.00€
Technological Area: 
Industrial Manufacture
Market Area: 
Solar energy

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