Optimized Dimensioning and Operation Automation for a Solar-Combi System for Indoor Space Heating. A Case Study for a School Building in Crete

Abstract

This article investigates the introduction of hybrid power plants for thermal energy production for the indoor space heating loads coverage. The plant consists of flat plate solar collectors with selective coating, water tanks as thermal energy storage and a biomass heater. A new operation algorithm is applied, maximizing the exploitation of the available thermal energy storage capacity and, eventually, the thermal power production from the solar collectors. An automation system is also designed and proposed for the realization of the newly introduced algorithm. The solar-combi system is computationally simulated, using annual time series of average hourly steps. A dimensioning optimization process is proposed, using as criterion the minimization of the thermal energy production levelized cost. The overall approach is validated on a school building with 1000 m2 of covered area, located in the hinterland of the island of Crete. It is seen that, given the high available solar radiation in the specific area, the proposed solar-combi system can guarantee the 100% annual heating load coverage of the examined building, with an annual contribution from the solar collectors higher than 45%. The annually average thermal power production levelized cost is calculated at 0.15 €/kWhth.

Working on Buildings’ Energy Performance Upgrade in Mediterranean Climate

“…Solar collectors have also been proposed and studied, starting from the installation of simple flat plate collectors for hot water production [22] to advanced systems, involving solar-combi systems for hot water production and indoor space heating [23][24][25], solar cooling with absorption chillers [26] and the newly introduced hybrid solar thermal photovoltaic panels for combined electricity and thermal energy production [27,28]. Solar-combi systems exhibit excellent applicability under the rich available solar radiation in the Mediterranean basin.…”

“…The proposed system has been proposed and constructed for two school buildings in Crete, aiming at the coverage of the indoor space heating load [23]. The layout of the proposed system is presented in Figure 12 [23].…”

“…These two discrete final energy uses are handled together with the introduction of a solar-combi system, which is highly favored, in this particular case, given the existing of final thermal power demand for both of the aforementioned uses during the whole annual period. The proposed system has been proposed and constructed for two school buildings in Crete, aiming at the coverage of the indoor space heating load [23]. The layout of the proposed system is presented in Figure 12 [23].…”

“…The operation algorithm is simple, presented in detail in [23]. The produced thermal power from the solar collectors is stored in the thermal storage tanks, on the condition of higher temperature of the working mean in the solar collectors' primary loop than in the thermal storage tank.…”

Temperature verification method of solar heat gains in installations with flat plate solar collectors – case study

“…Montoya-Márquez and Flores-Prieto analyzed the Heat Removal Factor and tilt angle for the flat plate collector (Montoya-Márquez and Flores-Prieto 2018). Katsaprakakis and Zidianakis optimized the cooperation of solar collectors with a biomass heater, using as a criterion the minimization of the cost of heat energy production at an increased level (Katsaprakakis and Zidianakis 2019). The Effect of the Inclination Angle on the Flat Plate Solar Collector Efficiency (in a Medium-Temperature) was investigated by Montoya-Marquez and Flores-Prieto (Montoya--Marquez and Flores-Prieto 2017).…”