Energy and environmental performances of small and innovative solar cooling systems

The development of renewable energy technologies is a critical tool for reducing climate change and the reliance on fossil fuels. However, renewable energy technologies cannot be considered totally clean because they require energy consumption and have environmental impacts that cannot be neglected during their life cycle. This paper presents the results of two researches related to the application of solar thermal system for building heating and cooling. It is focused on small and compact systems of two different typologies. An innovative compact Solar DEC system is analysed in terms of potential competitor of stand alone electrically driven HVAC systems. The performances of small absorption chillers coupled with low temperature solar collectors is investigated by the means of Life Cycle Assessment approach in order to highlight their environmental impacts also during manufacturing and end-of-life phases.Bajada New Energy, General Membrane, EcoGroup, Econetique, Energy Investment, JMV Vibro Blocks, Solar Engineering, Solar Solutionspeer-reviewe

NEW DEC OPEN CYCLE FOR AIR CONDITIONING BASED ON FIXED COOLED ADSORPTION BEDS AND WET HEAT EXCHANGERS

In this work, a new solar Desiccant Evaporative Cooling (DEC) concept is presented. In the proposed system, two fixed packed desiccant beds of silica gel, operating in a batch process, are used as an alternative solution to the common adsorption rotor for dehumidifying outside air. As well known, adsorption heat due to water condensation considerably reduces the dehumidification capacity of the desiccant material, causing inefficiencies in performance. The aim of the work is to overcome the mentioned intrinsic thermodynamic limit of the adsorption rotor technology. The proposed core component is a fin and tube heat exchanger, commonly used in several air conditioning applications, wherein the spaces between the fins are filled with silica gel grains. Therefore, the adsorption material is cooled through a water loop in connection with a cooling tower. An important feature of the system is the adsorption storage capacity, this is due to the high amount of desiccant material available. An indirect cooling process of the air is then realized by means of two wet evaporative heat exchangers connected in series, with continuous humidification of the secondary side. The thermodynamic cycle is first presented and simulation results are shown and discussed. Possible applications may concern compact roof-top units as well as common AHUs

Special issue "Smart Urban Lighting Systems"

The design and operation of multifunctional infrastructures for public lighting as well as their impact on the urban environment and citizens' life is today of great interest. The cost of energy for public lighting is often an issue for the budget of municipalities. Furthermore, researchers' and designers' attention is increasingly focused on aspects of public lighting not directly valuable through economic factors. Starting from the "quality" of the light environment, looking at citizens' visual comfort, the light has to be considered as an instrument to improve the urban context and objects therein (including buildings). Indeed, urban degradation (lack of infrastructures, maintenance, services, etc.) is linked to the poor quality of everyday issues, such as traffic, pollution, noise, lack of information, long times to access focal points, and the lack of safety. Simultaneously, in many areas, the potential related to the valorization of historical heritage is often underexploited. The installation of efficient lighting systems coupled with the implementation of ICT solutions can provide economic, social, and health benefits, energy efficiency, and visual comfort. On the other hand, as for indoor lighting, these systems can be expensive, not easy to maintain, and not as efficient as expected. The aim of this Special Issue was to investigate the problems and advantages of smart urban lighting systems in more detail. This Special Issue included 6 papers of the 10 submitted papers

Numerical evaluation on performances of AHU equipped with a cross flow heat exchanger in wet and dry operation

In this paper the comparison between the performance of a cross flow heat exchanger in wet and dry operation for air handling process has been investigated. In addition, a case study of application of the component to perform indirect evaporative cooling in a AHU was studied with the software TRNSYS. Using experimental data and an appropriate analytical method, energy saving performances of the system has been evaluated through the entire cooling season for a typical Mediterranean site. Results show that high energy saving potential can be obtained if the component is operated in wet operation in term of reduction of electricity consumption

Innovative Compact Solar Air Conditioner based on Fixed and Cooled Adsorption Beds and Wet Heat Exchangers

Abstract In this work, a new all-in-one compact solar air conditioner concept is presented. The system is mainly based on a new DEC process which utilises fixed and cooled adsorption beds operating in a batch process and two wet heat exchangers. The proposed innovative adsorption bed is a fin and tube heat exchanger commonly used in the air conditioning sector, wherein the spaces between the fins are filled with silica gel grains. The main feature of this component is to allow simultaneous dehumidification and cooling of air. Furthermore, since the component hosts a considerable amount of adsorption material, solar energy can be efficiently stored in the desiccant media in terms of accumulated adsorption capacity. This potential can be used when regeneration heat is not available, strongly reducing the need for thermal storage in the solar loop. The indirect evaporative cooling process, operated downstream to the dehumidification, is realized by two wet plate heat exchangers connected in series. The process can be operated at relatively low temperature, allowing supply air temperature to the room of about 20 °C. A prototype of the compact solar air conditioner specifically developed for residential application is presented. The main features of the system as well as the thermodynamic cycle are first described. Monitoring results are presented by means of most commonly used performance indicators showing several advantages which can be obtained using the proposed solution