The renewable energy lab aims to experimentally characterize solar thermal collectors. Throughout the years, several experimental tests were carried out on parabolic trough collectors (PTC), taking the standard ANSI/ASHRAE 93-2010 as reference.
UNIVPM.01 PTC prototype UNIVPM.02 PTC prototype
To date, the research is focused on the assessment of the performance of solar cookers, thermodynamic systems able to convert solar energy into thermal energy that can be exploited to heat up and cook food.
Solar box oven with a reflective mirror Heliac open solar concentration oven
Solar cookers are characterized by carrying out outdoor tests on the DIISM roof. Two tests are necessary to characterize a solar cooker:
No-load tests allow to determine the maximum temperature achievable by a solar cooker. Load tests, instead, are generally conducted with water (or other testing fluids, such as natural or diathermic oils) and allow to estimate the cooker specific/characteristic boiling times, power, optical and thermal efficiency.
Water tests results
Experimental tests with thermal storages based on phase change materials (PCMs) are carried out, too. PCMs are substances with a high latent heat of solidification/fusion, which can be used in solar cookers to improve their thermal stabilization during absence/intermittence of solar radiation.
To date, six solar cookers are under test in the lab:
Solar box cooker with high concentration ratio
In order to simulate variable thermal loads, the lab includes special vessels able to host both different testing fluids (water, natural/diathermic oils, etc.) and thermal storage systems based on phase change materials (PCMs). To date, several tests were carried out with the HITEC solar salt (a mixture of sodium and potassium nitrates) and with different commercial-grade sugars (erythritol, xylitol).
Thermal storage system based on solar salts
The lab also has an acquisition system to detect temperature by means of thermocouples, and NIP pyrheliometers to measure direct solar radiation.
Flow chart of the acquisition system
NIP pyrheliometers used to measure direct solar radiation
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