Renewable energy lab

Description

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 cookers can be classified according to the type of solar concentration:

solar box cookers, with or without booster mirrors;
concentrating (open) solar cookers, e.g. parabolic cookers or with different geometry.

Solar box oven with a reflective mirror Heliac open solar concentration oven

Research activities

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;
load tests.

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.

Facility

To date, six solar cookers are under test in the lab:

a solar box cooker with high concentration ratio;
a solar box cooker with medium concentration ratio;
an “open” concentrating solar cooker;
two low-cost solar box cookers with booster mirrors;
one low-cost concentrating solar cooker.

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).