New Perspective on Performances and Limits of Solar Fresh Air Cooling in Different Climatic Conditions

Abstract

The study carried out by simulation, concerns the thermal behavior of an office building’s solar fresh air cooling system, based on a LiBr-H2O absorption chiller in different climatic conditions. The coefficient of performance (COP) and the solar fraction were considered performance parameters and were analyzed with respect to the operating limits: risk of crystallization and maintaining at least a minimum degassing zone. A new correlation between the required solar hot temperature and the cooling water temperature was established and then embedded in another new correlation between the COP and the cooling water temperature that was used in simulations during the whole cooling season corresponding to each location. It was found that: the solar hot water should be maintained in the range of (80-100) °C depending on the cooling water temperature, the COP of the solar LiBr-H2O absorption chiller with or without cold storage tank can reach (76.5-82.4) % depending on the location, and the solar fraction can reach (29.5-62.0) % without cold storage tank and can exceed 100 % with cold storage tank, the excess cooling power being available to cover other types of cooling loads: through the building envelope, from lighting, from occupants, etc.

Preliminary sizing of solar district heating systems with seasonal water thermal storage

“…(4) were calculated on an hourly basis. For each moment, the tilt angle between the solar beam and the plane of the collector, was determined based on an algorithm presented in [ 58 , 59 ], that was already used and validated in previous studies at the Technical University of Cluj-Napoca, like [ 60 , 61 , 62 ]. This algorithm determines the following parameters: day angle; declination of the sun; equation of time; mean local time; solar time; hour angle of the sun; the angle of the solar altitude; the angle of the solar azimuth.…”