Performance study of a novel solar solid dehumidification/regeneration bed for use in buildings air conditioning systems

In this paper, a novel solar solid dehumidification/regeneration bed has been proposed, and its three regeneration methods, i.e., simulated solar radiation regeneration, microwave regeneration, and combined regeneration of the microwave and simulated solar radiation, were experimentally investigated and compared, as well as the dehumidification performance. The degree of regeneration of the proposed system under the regeneration method combining both microwave irradiation and simulated solar radiation could reach 77.7%, which was 3.77 times higher than that of the system under the simulated solar regeneration method and 1.05 times higher than that of the system under the microwave regeneration. The maximum energy efficiency of the proposed system under the combined regeneration method was 21.7%, while it was only 19.4% for the system under microwave regeneration. All these proved that the combined regeneration method of the simulated solar and microwave radiation not only improved the regeneration efficiency of the system, but also enhanced the energy efficiency. For the dehumidification performance, the maximum transient moisture removal was 14.1 g/kg, the maximum dehumidification efficiency was 68.0% and the maximum speed of dehumidification was 0.294 g/(kgμs) when the inlet air temperature was at 26.09 °C and the air relative humidity was at 89.23%. By comparing the testing results with the semi-empirical results from the Page model, it was indicated that the Page model can predict the regeneration characteristics of the novel solar solid dehumidification/regeneration bed under the combined method of microwave and simulated solar regeneration. The results of this research should prove useful to researchers and engineers to exploit the potential of solar technologies in buildings worldwide

On modelling moisture buffering when evaluating humidity controlled HVAC systems

As most building energy simulation programs focus on the thermal response of the building, the relative humidity of the indoor air is often calculated in a simplified way. One of the main shortcomings is the isothermal calculation, which may have a strong influence the predicted relative humidity. In this paper the use of a simplified effective moisture penetration depth (EMPD) model is compared with a coupled TRNSYS-HAM-model. First, an estimation of the load for humidification and dehumidification is made. Results showed that the EMPD-model underestimates the humidification load because the model disregards non-isothermal effects. Secondly, calculations showed that the indoor and surface relative humidity of an office room with a gypsum cooled ceiling are overestimated using the EMPDmodel. Furthermore, due to not including nonisothermal effects the peak load for dehumidifying the ventilation air may be underestimated using an EMPD-model

Development of concepts for a zero-fossil-energy greenhouse

Dutch government and greenhouse horticultural practice aim for strongly reduced fossil energy use and of environmental loads in 2010 and energy neutral greenhouses in 2020. This research aims to design a greenhouse concept with minimal use of fossil energy and independent of nearby greenhouses. The concept is called the zero-fossil-energy-greenhouse. This paper presents a theoretical design study and analysis to assess the viability of a zero-fossil-energy-greenhouse concept. The greenhouse was designed for Dutch circumstances and relies on available state-of-art technologies. Nine concepts were generated and evaluated by a panel of experts. Although, none of the concepts was unanimously selected, one of the concepts received on-average highest votes. It uses an aquifer for long term heat and cold storage. Geothermal heat and a heat pump connected to the warm pit of the aquifer are used to heat of the greenhouse. Electricity need is covered by green-electricity. Cooling and dehumidification of the greenhouse is realised by a heat pump combined with the cold aquifer pit. This concept was more thoroughly evaluated in a simulation study that assessed design consistency and evaluated greenhouse performance in view of design requirements. From the simulations it was concluded that a combination of geothermal heat and a heat pump/aquifer can cover the heat demand of the greenhouse with help of heat buffers, but a fully closed greenhouse concept is not manageable in the summer season. With given technology the chosen concept was not able to cool and dehumidify greenhouse air to target temperature and humidity. A semi closed greenhouse solves this problem

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

Approaches to Energy Efficiency in Air conditioning: Innovative processes and thermodynamics

Air conditioning in buildings has transformed our human lives greatly with work efficiency in commercial buildings and improved lifestyle in all weather. However, these improvements are accompanied with the negative effects from the emissions of greenhouse gases (GHG), both directly via refrigerant emissions and indirectly through electricity generation by the burning of fossil fuels. Although there were significant improvements in the efficacy of chillers since 2000, the kW/Ron of chillers for cooling for electrically driven DCS have reached an asymptotic level of 0.85±0.03 kW/Rton for the tropics and a 20% higher for the hot and dry arid climate. The levelling-off phenomenon of chillers' energy efficiency is attributed the improvements limits exploited from the efficacy of compressor and refrigerant technologies. Thus, an out-of-box solution, such as the decoupling of latent to sensible cooling in the dehumidification cum the indirect evaporative coolers (DH-IEC) to improve energy efficiency, It is projected that a quantum jump of 0.5 kWh/m3 or less is urgently needed for future sustainable cooling. In this paper, we adopted a top-down approach in evaluating the upper-bound energy savings of an economy if one were to employ the innovative DH-IEC cycle is assumed to be applied to the Singapore city state is highlighted with respect to the savings in the primary energy, emission of CO2 and the water savings of up to 40 % can be potentially achieved

Evaluation of electroosmotic pumping effect in microporous media flow

This paper was presented at the 3rd Micro and Nano Flows Conference (MNF2011), which was held at the Makedonia Palace Hotel, Thessaloniki in Greece. The conference was organised by Brunel University and supported by the Italian Union of Thermofluiddynamics, Aristotle University of Thessaloniki, University of Thessaly, IPEM, the Process Intensification Network, the Institution of Mechanical Engineers, the Heat Transfer Society, HEXAG - the Heat Exchange Action Group, and the Energy Institute.In this paper, the electroosmotic flow (EO) in desiccant powders of micro porous is investigated regarding to the flow rate caused by the electroosmosis and the gravity. In particular, the coupling effect of electroosmosis and dehumidification in the flow is studied. It is noticeable that the actual electroosmosis pumping force maintains at a certain rate (10μL/min for the designed system). It is interpreted that the actual voltage from bench power is kept constant which exerts same effect of electric field on the desiccant particles. And during this stage the resistance inside the channel deceases with the rate of water entering into the electroosmosis pumping section which is affected by the capacity of dehumidification of the desiccant particles. Moreover, the mass flow rate by the effect of electroosmosis pumping can be achieved at 0.746 gm-2m-1 under 5V DC supply. These experimental results in this study provide useful instructions of electroosmosis performance for designing the micro porous channel in such as filtering the compounds of drug delivery, particle purification and liquid separation applications etc

Advance Drying Technology for Heat Sensitive Products

This book presents the advance drying technology for heat sensitive products cited from international journals, handbooks, and current research of authors. In the first edition, the printing and publication was funded Diponegoro University. In this second edition, the publication was supported from Directory of Higher Education under competitive research grant. The topic discusses the current drying technology for heat sensitive product, challenges, development and application in accordance with high quality product as well as efficient energy usage. Unlike first edition, this book observes and evaluates several food products drying under air dehumidification. The conceptual process has been also submitted to Indonesian Patent 2014. In the first edition, the book consisted of 7 chapters. Whereas, in this second edition, the book was extended up to 10 chapters completed with application of air dehumidification for food drying. Chapter 1 discusses about the challenge and progress on drying technology development. Chapter 2 describes the application and research of vacuum and freezes dryer. It is followed by the concept of air dehumidified by zeolite for efficient drying, depicted in Chapter 3. Chapter 4 evaluates the conventional condenser and adsorption dryer for low temperature drying. Chapter 5 is an overview of microwave and radio frequency dryer. After that, Chapter 6 presents the types of dryers applied in industries involving tray, spray, fluidized, moving bed, and drum dryer. Chapter 7 evaluates the future possible development for innovative dryer namely adsorption dryer with zeolite for industry. Chapters 8, 9 and 10 present the application of air dehumidification for agriculture and food drying. These chapters are results of the research conducted during 2012 – 2014

The sunergy greenhouse - one yer of measurements in a next generation greenhouse

In summer, greenhouses have to deal with an excess of solar energy which is mostly discharged by ventilation. In moderate climates, on a yearly base this discharge of energy is comparable to the energy demand for heating. Thus, in times of growing awareness of the scarcity of fossil fuels, harvesting and storing of summertime heat excesses for application in winter seems to be a promising technique. Preferably the harvesting units are integrated in the greenhouse design because this enables the shared use of space and supporting constructions and the extraction of excess heat can improve the inside climate conditions, especially when one is trying to increase the inside CO2-concentration to above outside levels. However, although the concept sounds easy, in practice a lot of difficulties have to be overcome since there are strong limits to the affordable expenses, giving the value of the energy harvested. Moreover, the harvesting of summertime excesses and the application of the (low thermal) heat results in an important electricity demand for driving ventilators and a heat pump. This means that the ratio between heat and electricity demand shifts to the latter, which is unfavourable because of the much higher value of electricity compared to heat. Nevertheless, with a carefully designed energy harvesting greenhouse, promising opportunities appear to be achievable, especially when smart choices are made around the greenhouse air temperatures and humidity control. This paper presents the reasoning of such a design called the Sunergy Greenhouse. The proposed design was built as a 550 m2 demonstration object and has been in operation since June 2008. In this paper a number of results are presented and commented. Moreover, based on the observations, a simulation model was developed. With this model, amongst lots of other things, the impact of the prices of gas and electricity on the affordable costs of energy harvesting can be studied. The results, presented in this paper, help to understand business economical considerations

Study of the application of solar chemical dehumidification system to wind tunnel facilities of NASA Lewis Research Center at Cleveland, Ohio

Energy utilization and cost payback analyses were prepared for proposed modifications. A 50,000 CFM standard compact packaged solid desiccant dehumidifier utilizing high temperature hot water (HTHW) for desiccant regeneration was added. The HTHW is generated by utilizing solar energy and is stored in a storage tank. A steam boiler is provided as a back-up for the solar system. A 50,000 CFM standard compact package solid desiccant dehumidifier utilizing high temperature hot water (HTHW) for desiccant regeneration was added. The HTHW is generated by utilizing a steam boiler and a heat exchanger and is stored in a storage tank