Heat quantity measurement for solar thermal systems subject to calibration requirements
Solar thermal systems absorb solar radiation and convert it into usable thermal energy. This heat is used, among other things, for water heating or heating domestic buildings.
Due to the environmental fluctuation of the energy sources, solar thermal energy is used in addition to other energy sources in so-called bi- or multivalent systems.
Measuring the amount of heat when using solar thermal energy
In order to enable the use of solar thermal energy in systems with different users, calibratable measuring instruments should be used to measure the amount of heat. In addition, the recording of the "cold quantity" in cooling and refrigeration systems is supported.
For the approval of a calibratable measuring instrument, metrologically relevant parameters must be determined.
Product authorisation requirements for calibratable heat meters
The water and heat meter industry association Verband der Deutschen Wasser- und Wärmezählerindustrie e.V. (VDDW) - a corporate association of figawa - together with the German Arge Heiwako and the Physikalisch-Technische Bundesanstalt (PTB) are conducting investigations on the measurement uncertainty, measurement deviation and measurement stability of heat meters using various water-glycol mixtures as heat transfer media.
Within the framework of this joint project, test bases and certification procedures are developed and made available for placing on the market, well-known metrological procedures are further developed, new procedures for the experimental investigation of the influencing variables on the measurement uncertainty and measurement stability are developed, and the ageing behaviour of the water-glycol mixtures, concentration fluctuations, changes of the sound velocity and the influence of the flow velocities (laser measurement technology) are investigated.
These findings are incorporated into the PTB rules and regulations, one of the basic principles for the German Verification act, and support the process chain and quality assurance of the products.
The joint project is supported by a project support group from the circle of project partners. The Technical Committee Heat Meters leads the project within the VDDW e.V. and reports to the committees. The project is carried out at PTB Berlin, Department 7.6 "Heat".