Outdoor Environmental Conditions Research Articles

Mathematical modeling and study on the application of cross flow direct evaporative cooler under different indoor and outdoor environmental conditions

Performance of a cross flow direct evaporative cooler under different indoor and outdoor conditions was investigated by a thermodynamic model and using finite difference scheme. Unlike the previous studies, the temperature variation of water film during the evaporation process was included among the modeling, and the error of the mathematical model to estimate the effectiveness of the cooler became lower than the error reported in the literature. To achieve the comprehensive results and evaluation of the applicability of the system under real conditions, the performance of the cooler in ambient temperatures of 25, 30, 35 and 40 °C, relative humidities of 10, 30, 50 and 70% and cooling demand of 1–5 kW for a building with air changes of 5, 10 and 15 per hour was investigated. Lastly, the study on the performance of the cooler in different Iranian provincial capitals showed that for air change of 15 per hour and cooling demand of 1 kW, the system could provide thermal comfort conditions in 24 provincial centers while for air change of 5 per hour and cooling load of 5 kW, this goal cannot be achieved in any centers. Moreover, comparing the water consumption of the coolers showed that the maximum and minimum daily water consumption was for Yazd in September and for Kermanshah on July, respectively. Investigation of the coefficient of performance of the system for air changes of 10 and 15 per hour revealed that Khoramabad and Bandar Abbas had the maximum and minimum coefficients of performance, respectively.

NEW RECREATIONAL CATEGORY ASSOCIATED WITH COMMON WART TRANSMISSION

ABSTRACT Introduction “Altinha”, a variant of beach soccer that is very popular on the beaches of Rio de Janeiro, is a recreational activity that adapts the basics of beach soccer to a game with a circular formation, with the participation of several players who mainly use the following parts of their bodies: feet, legs, head, knees and trunk. Since it is a Brazilian pursuit, the relationship between “altinha” and skin infections is poorly described. The authors report six cases of patients diagnosed with common warts, seeking to correlate the development of these lesions with participation in “altinha”. Clinical Case Six patients, young adults from Rio de Janeiro who play “altinha” on Rio’s beaches, with complaints of painless verrucous lesions, were assessed. Physical examination revealed cracked normochromic keratotic papules mainly affecting feet and legs of the dominant limb. In light of the medical history and physical examination, the diagnosis was of vulgar warts. The patients were treated with cryosurgery, obtaining satisfactory results. Discussion The sport and its outdoor environmental conditions favor transmission of the human papillomavirus due to exposure to factors such as humidity, sweating and trauma, besides direct contact with the infected skin of other players and with colonized surfaces. “Altinha” is played barefoot, and the equipment of choice is the soccer ball, which is constantly shared between players, leading to trauma caused not only by the ball, but also by the sand. Moreover, the activity demands physical exertion from participants, resulting in sweating and potential physical contact. Conclusion With the increasing popularity of “altinha” among beachgoers, dermatologists must be aware of the sun protection habits of these individuals. They must also be mindful of the need to examine their skin for related dermatosis and to warn them of the risk of infection by the human papillomavirus in this new sport. Level of Evidence IV; Case series.

Combined Effect of Outdoor Microclimate Boundary Conditions on Air Conditioning System’s Efficiency and Building Energy Demand in Net Zero Energy Settlements

In Europe, near zero energy buildings (NZEBs) represent the new frontier of energy efficiency in the built environment. Shifting the scale from NZEBs to net zero energy (NZE) settlements represents the opportunity to achieve further energy, environmental, and cost benefits, thanks to shared energy management, optimization of renewable energy systems, and microclimate mitigation. In particular, the last aspect takes advantage of the implementation of local microclimate mitigation strategies at a larger scale to improve settlements outdoor environmental conditions and citizens’ wellbeing. Furthermore, this inter-building scale mitigation involves relatively less severe working boundary conditions for buildings, able to both reduce building energy demand and improve HVAC (heating, ventilation, and air conditioning) system’s efficiency. In this study, this potential extra-energy saving, achievable without additional costs, is explored within the framework of a NZE settlement built in Italy thanks to an ongoing Horizon 2020 project. Improved working conditions for the operating air conditioning system and building energy savings thanks to settlement scale opportunities for microclimate mitigation are assessed. Findings show how this effect represents a further non-negligible energy-efficient and environmentally sustainable benefit achievable through the design and construction of NZE settlements. Potential energy savings are up to 24% when considering the double effect of microclimate mitigation.

Production performance, inorganic nitrogen control and bacterial community characteristics in a controlled biofloc-based system for indoor and outdoor super-intensive culture of Litopenaeus vannamei

The aim of this study was to develop a commercial-scale biofloc-based tank system for shrimp culture in an efficient and environmental-friendly way. Eight independent and identical tanks (6 m/length × 6 m/width × 1 m/height, water volume of 30 m3) were randomly selected and prepared for the trial: four were from indoor and other four from outdoor. A complete production trial for super-intensive culture of L. vannamei was conducted under both indoor and outdoor environmental conditions simultaneously. In the trial, ten-day-old post-larvae of L. vannamei were stocked at a density of 580 ind m−3 and cultured for 13 weeks, obtaining survival rates of 82.7% and 81.3%, yields of 6.75 and 7.36 kg m−3, and FCRs of 1.32 and 1.25 under indoor and outdoor culture conditions, respectively. For producing one kg of shrimp, the usages of water, molasses and sodium carbonate were 210 L, 0.23 L and 0.27 kg under indoor condition and 217 L, 0.15 L and 0.19 kg under outdoor condition, respectively. Throughout the trial, the concentrations of both TAN and NO2−-N first increased and then decreased during the early to middle phases and then maintained below 1.0 mg L−1 until the end under both indoor and outdoor conditions. After mature bioflocs established in the culture water, diverse bacterial communities were detected from sampled bioflocs, with Shannon index significantly higher in outdoor than in indoor condition. Top eleven abundant phyla and top nine abundant genera of bacteria with relative abundance over 1% were all shared by both culture conditions, although most of them had significant differences in relative abundance between the two conditions. Notably, communities of nitrifying bacteria were detected in the bioflocs but with very low relative abundances under both culture conditions. Taken together, these results demonstrate the efficiency of a commercial-scale biofloc-based system for super-intensive culture of L. vannamei under limited water exchange. Moreover, the data suggest that the outdoor environmental conditions were more favorable in terms of production performance and inorganic nitrogen control of the system. Improved application of biofloc technology was also discussed and proposed for inorganic nitrogen control in intensive shrimp culture.

Association of the Indoor Environment With Dry Eye Metrics

The ocular surface is continuously exposed to the environment. Although studies have focused on associations between outdoor environmental conditions and dry eye, information on associations between the indoor environment and dry eye is lacking. To determine associations between the indoor environment and dry eye. This prospective cross-sectional study sample of 97 veterans with a wide range of dry eye metrics was recruited from the Miami Veterans Affairs Healthcare eye clinic from October 19, 2017, to August 30, 2018. Dry eye metrics were first evaluated in the clinic, followed by indoor home environmental metrics within 1 week using a handheld particle counter. Data were analyzed from October 19, 2017, to August 30, 2018. Symptoms of dry eye were assessed with standardized questionnaires. Dry eye signs were assessed via standard examination. Indoor environmental metrics included temperature, humidity, and particulate matter mass and count. Of the 97 participants included in the analysis, 81 (84%) were men, with a mean (SD) age of 58.2 (11.9) years. Dry eye symptoms were in the moderate range with a mean (SD) Ocular Surface Disease Index (OSDI) score of 31.2 (23.6). Humidity was associated with worse symptoms and signs, including OSDI score (r = 0.30 [95% CI, 0.07-0.49]; P = .01), inflammation (r = 0.32 [95% CI, 0.10-0.51]; P = .01), Schirmer score (r = -0.25 [95% CI, -0.45 to 0.02]; P = .03), eyelid vascularity (r = 0.27 [95% CI, 0.05-0.47]; P = .02), and meibomian gland dropout (r = 0.27 [95% CI, 0.05-0.47]; P = .02). In multivariate analyses, particulate matter of 2.5 μm or less (PM2.5) was associated with dry eye metrics when adjusted for demographic characteristics, comorbidities, medications, and interaction variables. For example, a 1-unit increase in instrumented PM2.5 level was associated with a 1.59 increase in the OSDI score (95% CI, 0.58-2.59; P = .002), a 0.39 reduction in Schirmer score (95% CI, -0.75 to -0.03; P = .04), a 0.07 increase in meibomian gland dropout (95% CI, 0.01-0.13; P = .02), and a 0.06 increase in inflammation (95% CI, 0.02-0.11; P = .009). When adjusting for humidity, this study found that increased particulate matter exposure was associated with worse dry eye metrics. Humidity was positively associated with dry eye metrics, potentially because higher humidity increases microbial growth and particulate matter size and mass.

Basil plants grown under intermittent light stress in a small-scale indoor environment: Introducing energy demand reduction intelligent technologies

Vertical farming is a novel type of farming for fresh food production in the urban environment. Vertical farms are located in indoor environments with artificial solar radiation, completely insulated and protected from outdoor environmental conditions. Since cultivated plant species need many hours of light daily to meet their growth requirements, energy costs are very high, which can be an inhibiting factor for the advancement of the technology. In this research study, we tested the growth rate of basil plants (Genovese species) under two lighting systems. At first, the plants were grown under 16 h of continuous light, and in the second lighting system, under a photoperiod of 14 h with intermittent light. The light intensity was stable in both treatments. The purpose was to determine if intermittent light exposure could reduce the energy consumption of basil grown in indoor environments sufficiently and efficiently without adversely affecting the growth rate and biomass production of the plants. The results of the study showed that the intermittent lighting system, in which light was emitted intermittently in short (10-min) light cycles, did not affect negatively the quality and quantity of basil plants. It was found that the short light intervals were not sufficient to attain the optimal photosynthetic efficiency of the cultivation, while the overall photosynthetic rate did not decrease significantly under the indoor conditions. Finally, the evaluation of the energy footprint under various light treatments can have a positive impact on the energetic, economic, business, and ecological phases of indoor food production.

Optimal price based control of HVAC systems in multizone office buildings for demand response

Optimizing the scheduling of heating, ventilation, and air-conditioning (HVAC) systems in multizone buildings is a challenging task, as occupants in various zones have different thermal preferences dependent on time-varying indoor and outdoor environmental conditions and price signals. Price-based demand response (PBDR) is a powerful technique that can be used to handle the aggregated peak demand, energy consumption, and cost by controlling HVAC thermostat settings based on time-varying price signals. This paper proposes an intelligent and new PBDR control strategy for multizone office buildings fed from renewable energy sources (RESs) and/or utility grid to optimize the HVAC operation considering the varying thermal preferences of occupants in various zones as a response of real-time pricing (RTP) signals. A detailed mathematical model of a commercial building is presented to evaluate the thermal response of a multizone office building to the operation of an HVAC system. The developed thermal model considers all architectural and geographical effects to provide an accurate calculation of the HVAC load demand for analyses. Further, Occupants’ varying thermal preferences represented as a coefficient of a bidding price (chosen by the occupants) in response to price signals are modeled using an artificial neural network (ANN) and integrated into the optimal HVAC scheduling. Furthermore, a control mechanism is developed to determine the varying HVAC thermostat settings in various zones based on the ANN prediction model results. The effect of the proposed strategy on aggregator utility with wider implementation of the developed mechanism is also considered. The optimization problem for the proposed PBDR control strategy is formulated using a building’s thermal model and an occupant’s thermal preferences model, and simulation results are obtained using MATLAB/Simulink tool. The results indicate that the proposed strategy with realistic parameter settings shows a reduction in peak demand varying from 7.19% to 26.8%, contingent on the occupant’s comfort preferences in the coefficient of the bidding price compared to conventional control. This shows that the proposed approach successfully optimizes the HVAC operation in a multizone office building while maintaining the preferred thermal conditions in various zones. Moreover, this technique can help in balancing the energy supply and demand due to the stochastic nature of RESs by cutting electricity consumption.

Comprehensive evaluation of energy and indoor-PM2.5-exposure performance of residential window and roller blind control strategies

The window with a roller blind inside can have huge impacts on solar heat gains and the air exchange between indoor and outdoor environments, but its potential value in terms of improving both building energy efficiency and indoor air quality is poorly understood. This study examines cooling energy consumption and indoor PM2.5 exposure concentrations from indoor and outdoor sources in Hong Kong dwellings under seven different window and roller blind control strategies. Dwellings with windows facing south were simulated for a selected week in April using EnergyPlus. The modelled control strategies (including conventional rule-based control and Genetic-Algorithm-based predictive control) accounted for thermal comfort and indoor and outdoor environmental conditions. A novel coupled-window-and-interior-roller-blind zone was developed in EnergyPlus and used to capture the impact of shading on ventilation performance. Results indicate that dwellings under the predictive window and roller blind control strategy used 55% less cooling energy than those with windows closed and roller blinds open, while meeting the World Health Organisation standard for PM2.5 exposure (25 µg/m3). Comparisons between control strategies also show that shading windows (which were open) in the early morning led to an increase in cooling energy consumption, whilst opening windows at night and shading them with roller blinds in the first half of the night offered the co-benefits of cooling through increased ventilation and the ability to reduce indoor PM2.5 exposure.

Numerical investigations of solar-assisted hybrid desiccant evaporative cooling system for hot and humid climate

This article presents numerical investigations of the solar-assisted hybrid desiccant evaporative cooling system integrated with standard air collectors for applications under the hot and humid climatic conditions of Kuwait city. The objective is to introduce the energy-efficient and carbon-free solar-assisted hybrid desiccant evaporative cooling system to alleviate the principal problems of electricity consumption and carbon emissions resulting from the use of the conventional vapor-compression cooling systems. In the normal building, during cooling load operation, the solar-assisted hybrid desiccant evaporative cooling system can cope with the cooling load particularly sensible by evaporative cooling and latent through desiccant dehumidification. The outcomes of this work indicate that solar-assisted hybrid desiccant evaporative cooling device integrated with air collectors is capable of providing average coefficient of performance of 0.85 and has the potential to provide cooling with energy saving when compared with conventional vapor-compression refrigeration systems. It was concluded that under the intense outdoor environmental conditions (ambient air at greater than 45°C and 60% relative humidity), the delivered supply air from the evaporative cooling was nearly at 27°C and 65% relative humidity. To solve this problem, the system was assisted with conventional cooling coil (evaporator of heat pump) to supply air at comfortable conditions in the conditioned space.

Transient simultaneous heat and mass transfer model to estimate drying time in a wetted fur of a cow

To reduce heat stress that contributes to complications in milk production and breeding, dairy cows are typically cooled by intermittent water sprays coupled with fan-induced air flow. Industry currently utilises fixed duration on and off-cycles; however, water efficiency may be improved by matching the sprinkler off-time to the cow drying time that corresponds to current outdoor environmental conditions. Electricity use can also be reduced by varying fan speeds to achieve the required heat rejection rate for a given set of conditions. To achieve savings in water and electricity, a transient, one-dimensional simultaneous heat and mass transfer model of evaporation within the wetted fur layer of a dairy cows was developed to estimate drying time and heat rejection rate based on ambient conditions. Water vapour concentration, liquid water content, and temperature within the fur layer were used to estimate a global drying time for fur. Model results was compared against a steady-state model in literature and the predicted net heat load is within 15% with a mean average error of 6.0%. Parametric analyses were performed to estimate drying time as a function of outdoor air temperature, air speed, humidity, and mean radiant temperature. Simulation results were used to develop a correlation for use in a control algorithm to predict the fan speed and sprinkler operation frequency needed to meet specified cooling load thresholds given outdoor conditions. Estimated savings demonstrated that the model-based controller could reduce annual electricity and water consumption by 20% and 40%, respectively. • Transient one-dimensional model for prediction of drying time from wetted cow fur. • Drying variation with outdoor temperature, humidity, air speed and roof temperature. • Predictive controller correlation based on regression of model simulation runs. • Controller shown to lower annual electricity by 20% and water consumption by 40%.

Radon kinetics in a natural indoor radon chamber

An unusual 180 m3 storage room in the basement of a two-story laboratory building is unventilated, and separated from occupiable rooms by double steel doors. The space completely borders on soil through the concrete floor and two of its concrete walls. The room also contains a separate inner chamber with 1 m thick concrete walls designed to damp vibrations in the room above it. The space boasts a relatively high radon level, 1083 Bq m−3, which varies with local outdoor environmental conditions. Measurements were made of radon concentrations at various locations and heights within the facility. More than a year of continuous radon concentration data corresponding to a single location are also available, along with measurements of indoor and outdoor pressure, temperature, and humidity. Data were also collected with as many as five fans placed in different locations and cycled on for variable time periods. First order linear kinetic models were created to explain the observed approaches to steady state due to changing conditions and wash-out resulting from intentional ventilation. Results demonstrate a good fit between changes in the radon concentration level and the developed compartmental models. However, no significant differences were observed between radon concentration at different locations or heights in the chamber.

Triboelectric-nanogenerator-integrated structural supercapacitor based on highly active P-doped branched Cu–Mn selenide nanowires for efficient energy harvesting and storage

A triboelectric nanogenerator (TENG) is an excellent tool for clean energy harvesting. Herein, we describe the development of a woven carbon fiber (WCF)-based multifunctional TENG-cum-structural supercapacitor and its connection via a rectifier so that the energy generated by the TENG is stored in the supercapacitor. The effectiveness of the WCF electrode was enhanced by growing P-doped Cu–Mn selenide nanowires on the surface. The polyester-based outer surface of the supercapacitor served as the positive electrode for the TENG and the polydimethylsiloxane-coated nanowire-WCF was the negative electrode. The integrated TENG generated 7.4 W m–2 of power, while the supercapacitor displayed energy and power densities of 97.21 Wh kg–1 and 54.25 W kg–1, respectively. The device retained excellent mechanical properties (strength: 583.11 MPa; modulus: 37.52 GPa; impact resistance: 69.91 J) after exposure to various outdoor environmental conditions. This type of device could mitigate the future energy demands of self-charging automobiles, electronics, and various outdoor applications.

Mean Age of Air in Natural Ventilated Buildings: Experimental Evaluation and CO2 Prediction by Artificial Neural Networks

The mean age of air (MAA) is one of the most useful parameters in evaluating indoor air quality in natural ventilated buildings. Its evaluation is generally based on the CO2 monitoring within the environment; however, other methods can be found in the literature, but they have not always led to satisfactory results. In this context, the present paper is focused on two main topics: the effect of the windows airtightness and of the environmental conditions on MAA and the application of artificial neural network (ANN) for the CO2 prediction within the room. Two case studies (case study 1 located in Terni and case study 2 located in Perugia) were investigated, which differ in geometric dimensions (useful area, volume, window area) and in airtightness of windows. The indoor and outdoor environmental conditions (air temperature, pressure, relative humidity, air velocity, and indoor CO2 concentration) were monitored in 33 experimental campaigns, in four room configurations: open door-open window (OD-OW); closed door-open window (CD-OW); open door-closed window (OD-CW); closed door-closed window (CD-CW). Tracer decay methodology, according to ISO 16000-8:2007 standard, was compiled during all the experimental campaigns. A feedforward ANN, able to simulate the indoor CO2 concentration within the rooms, was then implemented; the monitored environmental conditions (air temperature, pressure, relative humidity, and air velocity), the geometric dimensions (useful area, volume, window area), and the airtightness of windows were provided as input data, while the CO2 concentration was used as target. In particular, data of 19 experimental campaigns were provided for the training process of the network, while 14 were only used for testing the reliability of ANN. The CO2 concentration predicted by ANN was then used for the MAA calculation in the four room configurations. Experimental results show that MAA of case study 2 is always higher, in all the examined configurations, due to the higher airtightness characteristics of the window and to the higher volume of the room. When the difference between indoor and outdoor temperature increases, the MAA increases too, in almost all the investigated configurations. Finally, the CO2 concentration predicted by ANN was compared with experimental data; results show a good accuracy of the network both in CO2 prediction and in the MAA calculation. The predicted CO2 concentration at the beginning of experimental campaigns (time step 0) always differs less than 2% from experimental data, while a mean percentage difference of −18.8% was found considering the maximum CO2 concentration. The MAA calculated using the predicted CO2 of ANN was greater than the one obtained from experimental data, with a difference in the 0.5–1.3 min range, depending on the configuration. According to the results, the developed ANN can be considered an alternative and valuable tool for a preliminary evaluation of MAA.

Modeling the influences of layouts of residential townhouses and tree-planting patterns on outdoor thermal comfort in Bangkok suburb

In Bangkok, reducing the extreme heat in summer is a critical challenge for urban planners and researchers associated with the built environment. A significant cause of such extreme heat is the rapid expansion of residential development without corresponding planning and design. This work explores layout designs for residential townhouses, building geometries, and tree-planting patterns for enhancing outdoor thermal comfort in a Bangkok suburb. The microclimatic conditions of a total of 192 designs were simulated through modeling based on ENVI-met software. The climatic conditions were then transferred to the ENVI-met BioMET package to calculate the hourly physiological equivalent temperature (PET) values in a street canyon. The information was used to determine acceptable comfort conditions, as compared to an upper limit of outdoor thermal comfort from a prior work. It is found that the aspect ratio and street canyon orientation can significantly improve outdoor thermal comfort performance, as compared to increases in building density or decreases in tree-planting distance. Tree and building shade can reduce the PET value by 8.6 °C and 14.2 °C, respectively. For example, street trees can increase the outdoor thermal comfort conditions of an avenue canyon (H/W = 0.5–0.7) by up to 82%. However, building and tree shade cannot reduce the extreme conditions in E-W oriented canyons, as the overhead shade requires further protection from the angle of the sun's rays. The study's findings could assist in the development of new guidelines for the design and planning of residential townhouse projects for providing a cooler outdoor environment and comfortable conditions, especially in hot-humid areas of Bangkok.

Accelerated weathering studies of bioepoxy/ionic liquid blends: influence on physical, thermo-mechanical, morphology and surface properties

Ionic liquids are promising candidates with huge potential in combination with thermosetting polymers. However, the behavior of ionic liquid modified epoxy system towards outdoor environmental conditions are seldom reported. Therefore, it is interesting to study the effect of accelerated weathering on ionic liquid modified bioepoxy blends. In this work, bio-based epoxy resin and 1-Butyl-3-methylimidazolium chloride (BMIM[Cl]) ionic liquid blends were prepared by melt mixing method. The concentration of ionic liquid used was 0, 5, 10, 20, and 30 phr. The miscibility, morphology, thermo-mechanical, and surface hydrophilicity of the ionic liquid modified bioepoxy blends were studied before and after the accelerated weathering test. The miscibility of the blends was studied by Fourier transform infrared spectroscopy (FTIR). The FTIR results demonstrate the presence of charge transfer complexation reaction between ionic liquid and bioepoxy resin. The tensile strength and modulus were reduced while the elongation at break is increased with the addition of ionic liquid. On the other hand, the glass transition temperature and thermal stability of the bioepoxy blends were reduced with the addition of ionic liquid. The contact angle value increases with the incorporation of up to 10 phr ionic liquid, this is followed by a decrease. The interaction between the ionic liquid and bioepoxy resin has vanished after the weathering test. The elongation at break was reduced dramatically after the weathering test, especially for 20 and 30 phr blends. The thermal stability of the weathered samples is similar to that of the samples before weathering. While the Tg values of the blends are stable with respect to neat bioepoxy resin. On the other hand, the contact angle value of the bioepoxy blends increased after the weathering test due to the increased surface roughness after weathering.

Comparative Analysis of a Vision Based HGR System

The object tracking is critical to visual/video surveillance, analysis of the activity and gesture recognition. The major difficulties to be occurred in the visual tracking are different environmental conditions, illumination changes, occlusion and appearance. In this paper, the comparative analysis of the different systems which are used to recognize the head gestures under different environmental conditions is discussed. The existing algorithm used to recognize the head gestures has some limitations. The existing algorithm cannot work under outdoor environmental conditions. The traditional camshift algorithm and unscented kalman filter are integrated and used to recognize the head gestures under outdoor environmental conditions. The unscented kalman filter is a tracking algorithm used to remove the limitations of the traditional camshift algorithm. The simulation result shows the better performance of the improved algorithm than the traditional camshift algorithm.

Current collector optimizer topology to extract maximum power from non-uniform aged PV array

Centralized inverter technology is one of the most common architectures of the PV installation, which interfaces a large number of PV panels that configured in series-parallel (SP) combination to the grid. However, the power generated from centralized inverter architecture based on SP array topology is significantly reduced under the non-uniform aging condition. Non-uniform aging of PV panels is a common problem in the PV generation plants, as they often operate under harsh outdoor environmental conditions for a long service period. Due to the elevated price of replacing aged PV panels with new ones, it is preferable to improve the power extracted from aged PV systems. This paper proposes a circuit-based topology known as current collector optimizer (CCO) topology to enhance the performance of centralized inverter technology under the uneven aging condition of PV modules. According to the results, the maximum power extracted from the non-uniform aging PV array is substantially increased by using the CCO topology compared to the conventional SP array topology with bypass diodes. With CCOs, the PV array characteristics have a unique maximum power point (MPP) which can be easily followed by a simple MPP tracking algorithm, subsequently, the CCO topology does not suffer from misleading power losses. The proposed topology requires offline rearrangement of aged modules to obtain the optimum power if only the degradation rate of short-circuit current is used to assess the aging process. Furthermore, the CCO topology operates close to optimum power if the degradation rate of open-circuit voltage is taken into account.

Investigation of a binary eutectic mixture of phase change material for building integrated photovoltaic (BIPV) system

The incorporation of phase change material (PCM) into the building integrated semi-transparent photovoltaic (BISTPV) system is a promising technology to regulate the enhanced surface temperature of the photovoltaic (PV) system. In this work, Sodium Sulfate Decahydrate (Na2SO4·10H2O) and Zinc Nitrate Hexahydrate (N2O6Zn·6H2O) were mixed to form the binary eutectic PCM by heating mixing method. The results of Differential Scanning Calorimeter (DSC) characterization of those eutectic mixtures showed that the molar mass proportion of 70% weight of Na2SO4·10H2O and 30% weight N2O6Zn·6H2O was an optimum eutectic mixture for the solar energy applications. The developed eutectic mixture was employed in the specially designed and fabricated building-integrated semi-transparent photovoltaic phase change material (BISTPV-PCM) system to regulate BISTPV cell temperature. The experimentation was carried out at the outdoor environmental conditions in the region of Kovilpatti (9°10′0″N, 77°52′0″E), Tamilnadu, India throughout the year of 2018. The instantaneous peak temperature was reduced up to 12 ᵒC for the BISTPV-PCM system compared to the non-PCM counterpart. The annual output power generated from the BISTPV module was 34,287 W h/year which increased to 37,024 W h/year by using PCM.

Seasonal energy and environmental characterization of a micro gas turbine fueled with H2NG blends

This paper deals with the seasonal energy and environmental characterization of a commercial micro gas turbine fueled with hydrogen enriched natural gas blends, to implement a Power-to-Gas option. When the renewable electricity excess occurs in a hybrid system, that energy can be converted into hydrogen to increase micro-turbine environmental performance. The experimental approach consists of testing on field that device at rated and partial load over the hot and cold seasons. The energy and environmental performance, along with the method to properly allocate the pollutants emissions for such applications, have been presented when the hydrogen fraction ranges in 0% vol. - 10% vol, by means of a 2% vol. step. From the main findings it emerges that both heat recovery and electrical efficiency undergo a slight increase even if the machine is strongly affected by the environmental derating. However, the larger beneficial effects occurred over the summertime, since the hydrogen mixtures can partially offset the outdoor environmental conditions change. Indeed, beyond the hydrogen fraction of 6% vol. and beyond 15 kW of electric output, the enrichment increases the rotational speed providing a leaner combustion. In so doing, the CO emissions are equal to zero, while the NOx are almost constant.

Dynamic thermal simulation of advanced natural ventilation in buildings: current and future usage, UK exemplar

ABSTRACT This paper evaluates the use of advanced natural ventilation (ANV) strategies in a range of climatic conditions from four cities in the UK. A prototype ANV system was proposed to determine the most effective case in mitigating overheating. The case was then assessed under identical simulation conditions for all four ANV strategies. The overheating criteria used in the research include the single temperature criterion from CIBSE Guide A and the adaptive thermal comfort overheating criteria from BS EN 15251. Both the current and future ‘Design Summer Year (DSY)’ weather data were used to examine the thermal performances of the proposed design. The findings show that shading, night cooling and heavy weight structures (ceiling) were all useful in mitigating overheating, with night cooling being identified as the most effective measure. The work assessed the use of ANV in both current and future scenarios to quantify the limits of outdoor environmental conditions under which natural ventilation is an effective strategy for achieving thermal comfort. The adaptive thermal comfort overheating criteria were proved to be easier to meet compared with the CIBSE single temperature criterion. With the adaptive overheating criteria, the given design is predicted to not overheat until 2050 in London Heathrow; and for other places evaluated in the UK (Edinburgh, Manchester & Birmingham), the design passes these criteria. The Centre-in ANV strategies proved to be more effective than the Edge-in strategies for space cooling due to the extended structure thermal mass.