Heat exchangers for solar collectors

Thermal solar collectors are a technology using a reflective collector surface to gather solar radiation upon a receiver device, a pipe with a fluid flowing within used to absorb thermal energy and providing heat transfer. Heat collected by the working fluid can then be used to obtain electrical energy, by thermodynamics water/steam cycles.

Tempco has been contacted recently and involved in an innovative project related to renewable energy, a project for a parabolic trough solar collector, from an original idea of a research team at the Università Politecnica delle Marche, guided by eng. Marco Sotte, at the time committed in a phd at the university. After the building of a first prototype, the Univpm.01 structure, the team needed to test and measure the performances of the plant, requiring to engineer and build a test bench able to ensure the compliance of the solar collector system with the current regulations (Ashrae St. 93/2010 and UNI EN 12975).

Tempco was contacted to supply the heat exchanger, the core component of the solar collector test bench, called PTC.TestBench (PTC means parabolic trough collector): the project required specific parameters, indeed the PTC.TestBench needed to be used testing solar collectors in a wide range of temperatures, from 15 to 150°C, and working with both diathermic oil and water as heat transfer fluids. In addition, the team noticed that different thermal duties needed to be transferred by a constant fluid load on the same primary cycle of the heat exchanger.

“We were still having issues and questions in mind when we first met Tempco, after a search within different suppliers – says eng. Marco Sotte -: we have then built together a heat exchanger fully designed upon our requirements. The heat exchanger we are using has been sized according to the most challenging working conditions, and tested for any possible load status, and has brazed nickel plates able to resist to the highest temperatures, and avoiding corrosion in presence of demineralised water”.

The accurate informations given by Tempco on the functioning of the heat exchanger were also useful in order to correctly sizing all the others components of the circuit. The test bench has then been realized thanks to the collaboration of UnoImpianti in Rimini, that built the structure and put together the piping.

We are actually using with success the exchanger, being able to already gather great value first experimental results for our project. The skills, competence and support we found in Tempco were so precious, especially in the starting steps, when the project was an experiment and a new challenge for us too”.

Now a second prototype Univpm.02 of the parabolic trough collector has been completed in june 2012, equipped with and Alanod reflective surface and mounting an aluminium receiver having an outer diameter of 32 mm and a 50 mm external diameter glass cover with no evacuation. The first campaign of tests has been performed with water in an operative temperature range from 30°C to 75°C. Then a second campaign will start using heat transfer oil, and tests will be performed in a much larger range, up to an operative temperature of 150°C.

More information about this project @ http://www.marcosotte.eu/ptcproject/test-bench/