Air Conditioning Requirements Research Articles

Thermodynamic investigation of a new combined cooling, heating, and power (CCHP) system driven by parabolic trough solar collectors (PTSCs): A case study

A new solar-based, combined cooling, heating, and power system is designed and developed for the school of engineering at Urmia University in Urmia, Iran. The proposed arrangement consists of a solar subsystem with parabolic trough solar collectors, an organic Rankine cycle, two heating processes, and two single-effect absorption chillers. The system is thermodynamically studied for the summer air conditioning requirements, considering genuine energy demand and variable solar radiation in three different operational modes (solar, solar and storage, and storage modes). The influences on the system performance are assessed of varying three main variables including the number of days, organic Rankine cycle pump inlet temperature, and organic Rankine cycle turbine inlet pressure. The results demonstrate that the highest cooling, heating and electrical loads in the summer air conditioning are 896.9 kW, 228.5 kW, and 1500 kW, respectively. The energy load is provided by employing 449–1625 number of PTSCs throughout the year. Furthermore, for summertime the energetic and exergetic analyses reveal that the energy efficiency of the system in the solar mode, solar and storage mode, and storage mode is found to be 98%, 47.3%, and 98%, respectively. Accordingly, the exergy efficiencies were equal to 17%, 8.3%, and 17%.

A polydimethylsiloxane-coated metal structure for all-day radiative cooling

Radiative cooling is a passive cooling strategy with zero consumption of electricity that can be used to radiate heat from buildings to reduce air-conditioning requirements. Although this technology can work well during optimal atmospheric conditions at night, it is essential to achieve efficient cooling during the daytime when peak cooling demand actually occurs. Here we report an inexpensive planar polydimethylsiloxane (PDMS)/metal thermal emitter thin film structure, which was fabricated using a fast solution coating process that is scalable for large-area manufacturing. By performing tests under different environmental conditions, temperature reductions of 9.5 °C and 11.0 °C were demonstrated in the laboratory and an outside environment, respectively, with an average cooling power of ~120 W m–2 for the thin film thermal emitter. In addition, a spectral-selective structure was designed and implemented to suppress the solar input and control the divergence of the thermal emission beam. This enhanced the directionality of the thermal emissions, so the emitter’s cooling performance was less dependent on the surrounding environment. Outside experiments were performed in Buffalo, New York, realizing continuous all-day cooling of ~2–9 °C on a typical clear sunny day at Northern United States latitudes. This practical strategy that cools without electricity input could have a significant impact on global energy consumption. Radiative cooling can reduce air-conditioning requirements. In this study, the authors demonstrated an inexpensive thermal emitter that provided continuous daytime cooling up to 9 °C outdoors on a clear, sunny New York day.

Passive cooling in an urban setting

Radiative cooling can be used to reduce building air-conditioning requirements. In urban environments, nearby buildings partially block access to the sky, which hinders radiative cooling, but a thermal beam-shaping design can help solve this problem.

Investigation of the influence of groundwater seepage on the heat transfer characteristics of a ground source heat pump system with a 9-well group

The U-type ground heat exchanger is a significant component of the ground source heat pump (GSHP) system, transferring heat from the soil for the air conditioning requirements. Heat accumulation becomes a common problem for the practical application of such systems in southern China. Moreover, the buried pipes containing heat exchangers are constructed in a group form, making the heat accumulation situation more severe and complex. A 3-dimensional simulation model of a 9-well buried pipe group was established and validated by a thermal response test conducted in Nanjing, China. On the basis of this model, the influence of underground seepage water temperature and flow rate on thermal distribution was investigated. Subsequently, the heat transfer capacity of single-well depth in a heat exchanger under varying conditions was calculated. It is concluded that a serious heat accumulation occurs without groundwater seepage. With seepage flow, the heat accumulation can be dissipated. Lower seepage temperature has a modestly beneficial effect on the heat dissipation. The heat accumulation can be better dissipated and the heat transfer capacity per well depth can be improved with greater seepage flow rate.

A Review on Adsorbents In Chromatography

The Adsorption chromatography only differs from adsorption in how the process operates, not the principle of separation. For adsorption chromatography, the adsorbent is used as the stationary phase. The solute binds to the adsorbent via van der Waal forces and steric interactions. Since the adsorption sites are typical only on the outer surface of the stationary phase, fairly small particles are used as the stationary phase. The technique of chromatography used presently is limited to a few adsorbents and usually to non-aqueous systems, due to the difficulty of elution of the adsorbate. However, aqueous systems could be used if adsorbents were available which permitted adsorption and desorption to be controlled by pH adjustment. Adsorption is present in many natural physical, biological, and chemical systems and is widely used in industrial applications such as activated charcoal, capturing and using waste heat to provide cold water for air conditioning and other process requirements, synthetic resins, increase storage capacity of carbide-derived carbons for tunable nanoporous carbon and water purification.

Optimization Study of Parametric Thermal Bimetal Material Module for Green Building in Tropical Humid Climate

The largest energy consumption that we use is the consumption of electrical energy in terms of meeting the lighting needs and building air conditioning requirements (World Energy Consumption, 2016). According to the Ministry of Energy and Mineral Resources (2017), Indonesia’s largest energy use in commercial buildings is for flight systems (63%), lighting systems (20%), vertical transportation (7%) electronic devices (10%). The use of energy in the fulfillment of excessive needs result in worsening conditions on earth. Data can be a reflection of how the condition of the earth that we live at this time. Energy savings should be made to reduce the damage already occurring on this earth such as electricity usage savings, optimization of use of materials, the use of motor vehicles that cause air pollution, and others. The way that can be used to reduce artificial energy use is to utilize the existing passive building design such as the use of solar energy that can be maximized during the day, so that the use of electrical energy for lamps and artificial air conditioning. reduced. In addition, it can also be considered the optimal use of wind direction and speed that can suppress the use of Air Conditioner (AC) in excess. Building envelope with bimetal thermal material module application is part of kinetic architecture via biomimicry approach. Kinetic architecture is a concept where buildings are designed to allow parts of buildings to move without compromising the unity of the structural system. Approaches that can be applied in green building design is by optimizing bimetal material module that utilizes the thermal coefficient of a material. With this approach, building envelopes are improvised so that they can adapt to the existing environment. This research take location of case study in Kampung Juminahan, Yogyakarta, Indonesia which has characters of comunal housing.

Physiological thermal response in typical air conditioning Environment

Energy consumption for space cooling is increasing in Chinese residential buildings due to the extensive use of split air conditioners. To build a comfortable indoor environment and reduce energy consumption, comprehensive understanding about human thermal requirements of air conditioning is highly needed. As a reflection of human demand for indoor thermal environment, thermal sensation is usually under the effect of human physiological responses. For these reasons, a series of experiments were conducted in a climate chamber to understand human physiological thermal responses in air conditioning environment. During the experiments, indoor temperature was kept at 29°C in the first 30 minutes and then cooled down to 25°C in the next 30 minutes, after that, indoor temperature was held stable in the final 60 minutes. Twenty subjects were recruited to participate in the experiments. Results reveal that first, the temperature of limbs was lower than trunk due to the blood flood and clothing resistance, second, skin temperature and Thermal Sensation Vote(TSV) may still be in the dynamic change after the ambient temperature reached stable, third, significant linear correlation was found between skin temperature and TSV in the limbs, moreover, individual difference could be found in local skin temperature.

Indoor environment evaluation of a Dedicated Outdoor Air System with ceiling fans in the tropics – A thermal manikin study

Energy savings of the Air-Conditioning (AC) system is crucial in achieving energy conservation in buildings in the tropical region. A Dedicated Outdoor Air System with ceiling fans (DOAS-CF) aims to achieve energy savings arising from elevated room air temperature and minimizing the air-conditioning requirements. The objective of this study is to investigate the cooling effect produced by the DOAS-CF system at various locations in an AC room using a thermal manikin. The sedentary thermal manikin was set at three different locations such as under the ceiling fan, outside the fan blades and the center of the room at temperatures of 24 °C, 27 °C and 30 °C and at 60%RH with air velocities ranging from 0.02 m/s to 2.26 m/s at the height of 1.1 m. Two ceiling fans formed circulation airflows around each fan. High air speeds and low turbulence intensity were measured right under the ceiling fan and near the floor while low air speeds and high turbulence intensity were found at other locations. The cooling effect at the whole body of −3.3 °C was higher under the fan than that of −1.3 °C at other locations. The cooling effect was affected by temperature, location and fan speed mode significantly. The maximum cooling effect by manikin based equivalent temperature was higher than that by SET model due to an evaluation of the local cooling effect on each body part. The knowledge of the cooling effect is important and useful for a mechanical engineer to design the thermal environment produced by the DOAS-CF system.

The development of a clinical skills laboratory at Ross University School of Medicine.

Dedicated clinical skills laboratories (CSLs) that make use of models, mannequins and simulators, are being increasingly established in medical and veterinary schools. These have been commonplace in medical schools for more than two decades, but their incorporation within the teaching of veterinary curricula has occurred much more recently. In 2007, a decision was taken to establish a CSL at Ross University School of Veterinary Medicine. We considered the range of skills that we wished to teach, the physical space and equipment needed, the storage and air conditioning requirements, the facilities needed to deliver PowerPoint lectures and case study presentations, and other essentials necessary to handle cadaver specimens. We converted an appropriate campus building to our needs, hired teaching staff, and started to source models and mannequins for the teaching of veterinary clinical skills. In 2010, 177 senior students completed a survey evaluating their experiences within our CSL. Student satisfaction was generally high, with 95% of respondents feeling that the CSL had improved their psychomotor skills. However, 15% of them felt that the models were insufficiently realistic. Our clinical skills programme has since developed considerably, and it currently offers instruction in a diverse array of surgical, medical and other clinical skills. We hope that this description of our experiences may assist others embarking on similar projects elsewhere.

High quantum yield of the Egyptian blue family of infrared phosphors (MCuSi4O10, M = Ca, Sr, Ba)

The alkaline earth copper tetra-silicates, blue pigments, are interesting infrared phosphors. The Ca, Sr, and Ba variants fluoresce in the near-infrared (NIR) at 909, 914, and 948 nm, respectively, with spectral widths on the order of 120 nm. The highest quantum yield ϕ reported thus far is ca. 10%. We use temperature measurements in sunlight to determine this parameter. The yield depends on the pigment loading (mass per unit area) ω with values approaching 100% as ω → 0 for the Ca and Sr variants. Although maximum quantum yield occurs near ω = 0, maximum fluorescence occurs near ω = 70 g m−2, at which ϕ = 0.7. The better samples show fluorescence decay times in the range of 130 to 160 μs. The absorbing impurity CuO is often present. Good phosphor performance requires long fluorescence decay times and very low levels of parasitic absorption. The strong fluorescence enhances prospects for energy applications such as cooling of sunlit surfaces (to reduce air conditioning requirements) and luminescent solar concentrators.

The Impact of Drive Cycles and Auxiliary Power on Passenger Car Fuel Economy

In view of the advancement of zero emission transportation and current discussions on the reliability of nominal passenger car fuel economy, this article considers the procedure for assessing the potential for reducing the fuel consumption of passenger cars by using electric power to operate them. The analysis compares internal combustion engines, hybrid and fully electric concepts utilizing batteries and fuel cells. The starting point for the newly developed, simulation-based fuel consumption analysis is a longitudinal vehicle model. Mechanical power requirements on the drive side incorporate a large variety of standardized drive cycles to simulate typical patterns of car usage. The power requirements of electric heating and air conditioning are also included in the simulation, as these are especially relevant to electric powertrains. Moreover, on-board grid-load profiles are considered in the assessment. Fuel consumption is optimized by applying concept-specific operating strategies. The results show that the combination of low average driving speed and elevated onboard power requirements have severe impacts on the fuel efficiency of all powertrain configurations analyzed. In particular, the operational range of battery-electric vehicles is strongly affected by this due to the limited storage capacity of today’s batteries. The analysis confirms the significance of considering different load patterns of vehicle usage related to driving profiles and onboard electrical and thermal loads.

Developmens of alternative systems for automotive air conditioning - A review

Vapor-compression refrigeration (VCR) systems are still the most widely used type of automotive air conditioning (A/C) systems in spite of their high energy consumption and negative environmental effects. Although the significant amount of research conducted during the last three decades, the automotive alternative (A/C) systems are yet immature. Despite some remaining constraints only (VCR)-type of A/C systems, powered by electric energy and used in EV’s, have reached the commercialization level. Also thermoelectric A/C systems powered by recovered exhaust energy and used for seat occupant cooling as well as (VCR) A/C systems powered by solar energy, are developed to the extent that they can be commercialized in the near future. Whereas the other alternative systems still suffer from many challenges that make them unable to satisfy the severe requirements of automotive air conditioning. Among those challenges: Large system size and complexity which do not realistically work in the demanding automotive environment, low coefficient of performance (below one for most of them) which prevents them from competing with the conventional (VCR) systems, high initial cost and lack of enough heat to power most of the systems. However alternative A/C systems have the advantage of being eco-friendly. A future development roadmap is presented to overcome the above-mentioned challenges.

Optimal design of air-conditioning systems using deep seawater

This paper presents a multi-objective mixed integer linear programming problem for the optimization of seawater air-conditioning systems using deep seawater as a cooling utility. The optimization formulation was developed including the technical, economic and environmental aspects of the problem. The model is used to define the optimal scheduling of deep seawater use and electricity needed to satisfy the air-conditioning requirements in a group of hotels. It also addresses the optimal planning for biocide, neutralization chemical dosing and mechanical maintenance required to maintain optimal operation conditions in the system. The proposed model is applied to a case study in Mexico. Results show the trade-offs between economic and environmental aspects. Optimal solutions compensating economic and environmental objectives are identified through a Pareto front.

The impact of surgery on global climate: a carbon footprinting study of operating theatres in three health systems

Climate change is a major global public health priority. The delivery of health-care services generates considerable greenhouse gas emissions. Operating theatres are a resource-intensive subsector of health care, with high energy demands, consumable throughput, and waste volumes. The environmental impacts of these activities are generally accepted as necessary for the provision of quality care, but have not been examined in detail. In this study, we estimate the carbon footprint of operating theatres in hospitals in three health systems. Surgical suites at three academic quaternary-care hospitals were studied over a 1-year period in Canada (Vancouver General Hospital, VGH), the USA (University of Minnesota Medical Center, UMMC), and the UK (John Radcliffe Hospital, JRH). Greenhouse gas emissions were estimated using primary activity data and applicable emissions factors, and reported according to the Greenhouse Gas Protocol. Site greenhouse gas evaluations were done between Jan 1 and Dec 31, 2011. The surgical suites studied were found to have annual carbon footprints of 5 187 936 kg of CO2 equivalents (CO2e) at JRH, 4 181 864 kg of CO2e at UMMC, and 3 218 907 kg of CO2e at VGH. On a per unit area basis, JRH had the lowest carbon intensity at 1702 kg CO2e/m2, compared with 1951 kg CO2e/m2 at VGH and 2284 kg CO2e/m2 at UMMC. Based on case volumes at all three sites, VGH had the lowest carbon intensity per operation at 146 kg CO2e per case compared with 173 kg CO2e per case at JRH and 232 kg CO2e per case at UMMC. Anaesthetic gases and energy consumption were the largest sources of greenhouse gas emissions. Preferential use of desflurane resulted in a ten-fold difference in anaesthetic gas emissions between hospitals. Theatres were found to be three to six times more energy-intense than the hospital as a whole, primarily due to heating, ventilation, and air conditioning requirements. Overall, the carbon footprint of surgery in the three countries studied is estimated to be 9·7 million tonnes of CO2e per year. Operating theatres are an appreciable source of greenhouse gas emissions. Emissions reduction strategies including avoidance of desflurane and occupancy-based ventilation have the potential to lessen the climate impact of surgical services without compromising patient safety. None.

The impact of climate change on air conditioning requirements in Andalusia at a detailed scale

This work calculates the current heating and cooling degree days and also examines heating and cooling degree days in relation to three subdivisions of the twenty-first century. On the basis of these data, we were able to calculate the heating and cooling degree months and degree years. After examining both sets of data, we studied the total needs of air conditioning—also referred to in the current paper as climatization needs——for Andalusia as a whole. The results indicate an increase in air conditioning needs, and we also noted that the areas adversely affected by this increase were more numerous than those which benefited, at the end of the century. It should be noted that climate change will also necessitate the gradual replacement of heating with cooling, which will require profound changes in the energy, land planning, and housing policies of the region. The true magnitude of the challenge becomes clear when the climatization degree days are related to the population which they affect; the majority of the population is located in areas where the climatization needs will increase over the course of the century. Undoubtedly, this issue is a major protagonist in the climate change adaptation process in Andalusia.

Integración de tecnologías energéticamente eficientes en sistemas de climatización operados con energía térmica

Con el artículo se pretende mostrar el desarrollo de un proyecto demostrativo y educativo de un sistema de climatización operado con energía solar, en el cual se usan tecnologías complementarias energéticamente eficientes que potencien su desempeño dentro del bloque de registro de la Universidad Pontificia Bolivariana (UPB), así mismo potenciar la investigación, desarrollo e inversión para conseguir una alta penetración de tecnologías de climatización eficiente y limpia. El desarrollo se ha dividido en 4 grandes fases, que inician con la simulación del sistema de refrigeración, en el cual se ha utilizado el software TRNSYS®; dimensionamiento y diseño básico del sistema de refrigeración; búsqueda y selección de equipos p.e. bombas; máquina de absorción, colectores solares, entre otros; diseño de detalle de un sistema de climatización con energía solar térmica, en el cual se hace uso de un equipo de enfriamiento de agua por absorción, paneles radiantes y enfriador evaporativo indirecto. Entre los resultados obtenidos se encuentra el dimensionamiento y diseño detallado del sistema y la adquisición del equipo de absorción y enfriamiento evaporativo soportados en un diseño simulado al emplear los softwares TRNSYS® y MATLAB®. Lo anterior permitió determinar los niveles de carga adecuados para cada uno de los equipos involucrados en el sistema, además de asegurar los parámetros de calidad de potencia para atender los requerimientos de energía eléctrica y aire acondicionado.

Solution to Avoid Power Crisis in Telangana State by Implanting Non Convectional Energy

<div><p><em>Perennial Efforts to combat power crises in newly found Telangana state, compelled to use hybrid source of power which is being catered to facilitate the needs of modern trends, life style, multinational business requirements which enforced the need to explore the modern application of solar energy run household and administrative block. Air conditioning requirement, which consumes more than 30% of the state procured power from different sources, which can be save and utilize for agriculture sector and other constructive needs.</em></p><p><em> In Telangana State every commercial, administrative and elite residential block is equipped with air conditioning system where the temperature ranges between 32-43<sup>0</sup>C in summer season. Telangana State is attracting the world class business investors. This design can caters the world class needs therefore this paper explore the design and performance of solar power air-conditioning system, which is integrated with invertors, PV panels, solar charger and batteries. This design can be used in non-electrified rural arid areas to avoid the expenses of supplying electricity.</em></p><p><em> This research project begins with the cooling load calculations for the selected space ideally whose dimensions are assumed to be one tone of refrigeration (3.5kW). Considering the basic parameters of cooling the photovoltaic cells has been deduced and necessary connections are arranged. </em></p><p><em> To acquire the inlet and outlet temperatures of compressor, evaporator and condenser, data logging procedure is employed. The input power for this system as well as coefficient of performance for above said climatic conditions can be deduced. The COP varies from two to four for this system and these results are compared with the convectional system performance they both match with each other considerably.</em></p></div>

Experimental investigation on waste heat driven activated carbon-methanol adsorption cooling system

This paper presents design and fabrication of an adsorption refrigeration system working with activated carbon-methanol and coupled to the exhaust system of a multi-cylinder turbo-charged diesel engine. We have also carried out experiments to study the cycle time, refrigeration effect and COP of the cycle. This paper is reported of the original experimental data obtained from experimentation of a real adsorption refrigeration setup. We have studied and reported the effects of minimum bed temperature (T 1) and maximum bed temperature (T 3), the two most important parameters influencing the performance of an adsorption refrigeration system. From experimental result it is observed that the maximum temperature (T 3) of the cycle should be kept as high as possible to generate higher volume of methanol from the activated carbon and, hence, higher refrigeration effect and COP. Since, the temperature of hot water circulated through the desorption bed has been restricted to 90 °C, it takes long time duration to achieve T 3 above 80 °C and hence, during the experiment, the maximum temperature of the bed (T 3) has been limited to 80 °C. It is also observed that the minimum temperature of the bed (i.e., the temperature of the bed after end of adsorption) (T 1) should be kept as low as possible to optimize COP of the cycle. The experimental results show that, for T 1 of 30 °C and T 3 of 80 °C, the maximum refrigeration effect is 1519.41 kJ per cycle for the given configuration of the refrigeration system and the cycle COP is 0.21. Uncertainty analysis predicts that variation of experimental COP varies between ±6.59%. This paper also presents different practical problems that faced by the authors during fabrication of the setup, for the benefit of the future researchers. The study also aims to comment on the capability of meeting the air-conditioning requirement of a vehicle by the waste heat associated with exhaust gases only, without requiring any extra power from the engine, thereby reducing fuel consumption and environment pollution.

Modelling of Shaded and Unshaded Shallow-Ground Heat Pump System for a Residential Building Block in a Mediterranean Climate

Heat pumps may be coupled to shallow-ground geothermal fields and used for the purpose of space heating and cooling of buildings. However, quite often it is not possible to locate the geothermal field in cleared grounds, especially in cities where building density is high and land has a high premium. This leads to the possibility of burying the geothermal field under the basement of new building blocks, before construction of the building.In the present work, the shaded-unshaded arrangement is numerically studied by coupling the software DesignBuilder-EnergyPlus to assess the building’s energy requirement with the software FEFLOW to solve the heat transfer equation in porous media. Assuming a standard residential building block, the coupling between the two software is performed by assigning the thermal energy requirement for air conditioning, as calculated by EnergyPlus, to a flat-panel typology of ground heat exchanger simplified in a 2D FEFLOW’s domain.The results show that it is necessary to opt for a dual-source heat pump (air/geothermal) system to ensure that the ground is not frozen or over-heated at peak times and to improve the overall performance of the system.

Experimental investigation on the thermal performance of heat storage walls coupled with active solar systems

This paper presents an experimental investigation of the performance of a system combining a low-temperature water wall radiant heating system and phase change energy storage technology with an active solar system. This system uses a thermal storage wall that is designed with multilayer thermal storage plates. The heat storage material is expanded graphite that absorbs a mixture of capric acid and lauric acid. An experiment is performed to study the actual effect. The following are studied under winter conditions: (1) the temperature of the radiation wall surface, (2) the melting status of the thermal storage material in the internal plate, (3) the density of the heat flux, and (4) the temperature distribution of the indoor space. The results reveal that the room temperature is controlled between 16 and 20 °C, and the thermal storage wall meets the heating and temperature requirements. The following are also studied under summer conditions: (1) the internal relationship between the indoor temperature distribution and the heat transfer within the regenerative plates during the day and (2) the relationship between the outlet air temperature and inlet air temperature in the thermal storage wall in cooling mode at night. The results indicate that the indoor temperature is approximately 27 °C, which satisfies the summer air-conditioning requirements.