Storage Tank Volume Research Articles

The photovoltaic-thermal system parameter optimization design and practical verification

This study used the Taguchi method combined with Analytic Hierarchy Process (AHP) to present optimization design of the Photovoltaic-Thermal (PV/T) system for improving the two quality characteristics namely electrical and thermal efficiency. The control parameters for PV/T design including the collector plate material, collector azimuth, number of collector tubes, mass flow rate, collector angle, and storage tank volume to area (V/A) ratio are crucial factors affecting the performance of the PV/T. First, Taguchi method coupled with main effect analysis (MEA) and analysis of variance (ANOVA) was used to obtain the best parameters combination on each single quality characteristic of electricity and thermal efficiency. In order to achieve the maximum total efficiency of the PV/T system, multi-quality analysis AHP was used to obtain the optimal control parameters combination according to the contribution degrees of quality weight. Then, the computational fluid dynamic (CFD) software used to simulate the PV/T module thermal distribution before and after optimization. The optimization control parameters combination are: collector plate material is copper, collector azimuth is due south, number of collector tubes is 12, mass flow rate is 0.01 kg/s-m2, collector angle is 25°, and V/A ratio is 123. The effectiveness of the proposed method was evaluated by the confirmation experiments. The optimization properties under these parameters are electrical efficiency 14.29% and thermal efficiency 44.96% which is improved than traditional PV/T system (electrical efficiency 12.74% and thermal efficiency 34.06%). The findings of CFD showed that the temperature of the PV/T module decreased by about 10 °C after optimality analysis, and the coefficient of correlation between the simulated and actual PV/T water temperatures was 0.991 (very close to 1). The CFD simulated performance testing proposed in this study has a good verification effect.

Rainwater harvesting systems reduce detergent use

Due to population growth, urban water demand is expected to increase significantly, as well as the environmental and economic costs required to supply it. Rainwater harvesting (RWH) systems can play a key role in helping cities meet part of their water demand as an alternative to conventional water abstraction and treatment. This paper presents an environmental and economic analysis of RWH systems providing households with water for laundry purposes in a life cycle thinking perspective. Eight urban RWH system scenarios are defined with varying population density and storage tank layout for existing buildings. Storage tank volume required is calculated using Plugrisost software, based on Barcelona rainfall and catchment area, as well as water demand for laundry, since laundry is a fairly constant demand of non-potable water. Life cycle assessment (LCA) and life cycle costing (LCC) methodologies are applied for this study. Environmental impacts are determined using the ReCiPe 2008 (hierarchical, midpoint) and the cumulative energy demand methods. Net present value (NPV), internal rate of return (IRR), and payback (PB) time were used in LCC. Savings from laundry additives due to the difference in water hardness was, for the first time, included in a RWH study. LCA results indicate that the best scenario consists of a 24-household building, with the tank spread on the roof providing up to 96% lower impacts than the rest of scenarios considered. These results are mainly due to the absence of pumping energy consumption and greater rainwater collection per cubic meter of built tank capacity. Furthermore, avoided environmental impacts from the reduction in detergent use are more than 20 times greater than the impacts generated by the RWH system. LCC indicates that RWH system in clusters of buildings or home apartments offer up to 16 times higher profits (higher NPV, higher IRR, and lower PB periods) than individual installations. LCA and LCC present better results for high-density scenarios. Overall, avoided environmental and economic impacts from detergent reduction clearly surpass environmental impacts (in all categories except terrestrial acidification) and economic cost of the RWH system in most cases (except two scenarios). Another important finding is that 80% of the savings are achieved by minimizing detergent and fabric softener by using soft rainwater; and the remaining 20% comes from replacing the use of tap water.

Pendulum Modeling of Sloshing Motion Using Particle Swarm Optimization

In this paper, we propose a technique for modeling the sloshing phenomenon as a pendulum. Sloshing model is generated under gravity conditions for nine inner mass ratios to the storage tank volume and 12 input types. The mass ratio ranges from 10 to 90%, in units of 10%. The input is divided into three types and four levels of magnitude. The particle swarm optimization algorithm, which is a metaheuristic method, is applied to perform the pendulum modeling. The pendulum consists of three variables: the mass ratio of the pendulum to the inner fluid mass, length, and damping coefficient. Using the optimized pendulum modeling variables for 108 cases, we analyze the change in pendulum model parameters due to the variation in the inner fluid mass and input.

Impacts of hot water consumption pattern on optimum sizing and techno-economic aspects of residential hybrid solar water heating systems

Hot water consumption pattern culture, appropriate sizing of solar water heating (SWH) systems, governmental policies and incentives on renewable energy projects, and climate conditions are factors that can affect the techno-economic and environmental performance of hybrid water heating systems. This paper aims to simultaneously include these factors in techno-economic modeling of hybrid water heating (HWH) systems. Different domestic hot water (DHW) consumption patterns are considered. The required hot water for space heating is calculated for a typical dwelling located in Shiraz, Iran. Electricity and natural gas water heaters are considered as auxiliary systems. The appropriate sizing of the solar system to achieve the desired techno-economic performance is obtained. The results show that the optimum ratio between storage tank volume and collectors field area to achieve up to 90% of solar fraction, does not exceed 0.08 m in all cases. By liberalizing the energy price, 80–90% of DHW consumption can be supplied by SWHs at a viable price. When the space heating is also included, the collector field area, storage tank volume, and solar fraction reach to 50 m2, 1.4–1.9 m3, and 50%, respectively, in most economic design where 42.7–45.3% lower price is achieved.

Research on the design of hydrogen supply system of 70 MPa hydrogen storage cylinder for vehicles

A hydrogen supply system of 70 MPa hydrogen storage cylinder on vehicles is designed, in which a compressor is proposed to use the new type of ion compressor. The system is simulated statically by Aspen Plus. Meanwhile, during the process of hydrogen charged from the third-stage high-pressure hydrogen storage tank to the hydrogen storage cylinder on vehicles, the dynamic variety of the third-stage high-pressure hydrogen storage tank is simulated dynamically by Aspen HYSYS Through the simulation, obtaining the results that there are difference between theoretical calculation and simulation for the volume of third-stage high-pressure hydrogen storage tank and the average volume flow of hydrogen in a third-stage high-pressure hydrogen storage tank varies with its pressure and volume. By comparing the results of Aspen Plus simulation and Aspen HYSYS simulation, there are some differences. The designed system can be applied to hydrogen stations and any operating conditions involving the supply hydrogen.

Residential use of solar water heating in Turkey: A novel thermo-economic optimization for energy savings, cost benefit and ecology

Recent trends in residential solar water heating and its efficient usage in Turkey were presented in this study. A novel methodology for determining the optimum orientation and sizing of water-in-glass evacuated tube solar water heating systems has been outlined. Transient modeling was conducted for the prediction of a full year's system performance via the System Advisor Model. In this model, the typical meteorological year data of certain climate zones in Turkey were considered, daily hot water consumption was estimated using the Rand hot water profile, and the monthly averaged mains water temperatures measured by the municipalities were analyzed. In addition, a typical performance rating of a water-in-glass evacuated tube collector produced by the collector manufacturer in Turkey was taken into consideration, and the effects of collector area, storage tank volume, daily average delivery temperature and daily hot water consumption data on the annual solar fraction were analyzed. The verification of the simulation results were compared with the literature and good agreement was obtained. Subsequently, a thermo-economic optimization was employed by using P1‒P2 methodology. The methodology presented guarantees to obtain reliable results with a minimal run-time. The diminution in the initial system cost and payback period are shown to be possibly achieved at the level of 7.5% in a 1.5 year period, respectively, while the energy savings are approximately 12% higher annually when implementing optimum results. The results indicate that Turkey would save 300 MWth annually if evacuated tube solar water heaters in Turkey's cities are configured based on optimal sizing. An evacuated solar water heater in a typical residential building in Turkey has the potential to mitigate 5–22 g CO2-equivalent/kWh of greenhouse gas emissions per annum if properly installed.

Daily, monthly and yearly performance of a linear Fresnel reflector

The main objective of this study is to investigate the daily performance of a linear Fresnel reflector in energetic and exergetic terms. The collector is designed and examined in SolidWorks Flow Simulation in order to obtain the optical and thermal efficiency curves. These data are inserted in a developed numerical dynamic model for the prediction of the daily performance of the solar collector which is coupled to a storage tank. The collector has total aperture 27 m2, concentration ratio 20.46 and the storage tank volume is 3 m3. The system is investigated for twelve typical days, one for each month, and its yearly performance is determined by taking into consideration only the sunny days of every month. According to the final results, the mean yearly incident angle modifier is found to be 37% while the maximum yearly exergy efficiency is 8.0% when the system starts with 450 K inlet temperature at the morning. For this case, the mean yearly thermal efficiency is found to be 18.5% and also June is the month with the highest thermal and exergy outputs. Furthermore, it is important to state that the mean daily incident angle modifier is found to be the 81% of the maximum daily incident angle modifier for all the months.

Improving the Energy Efficiency of the ATAD System through Redesign using Integration Superstructure

The aim of this study is application of an approach for solution of two-stage stochastic optimization problem for design of heat-integrated Autothermal Thermophilic Aerobic Digestion (ATAD) bioreactors system for municipal wastewater treatment operating under uncertainties. It incorporates in a common superstructure of two models of heat integration with one heat storage tank and two heat storage tanks for storing the heat used for preheating the incoming into the ATAD system cold raw sludge. On the first stage of the approach heat exchanger networks areas and the volumes of the heat storage tanks are determined. On the second stage - the flows rates represented by respective heating and cooling times are determined. As an optimization criterion - the annual capital costs for needed for the purpose of redesign of the ATAD system equipment as heat exchangers, heat storage tanks and pumps is determined as well as operating costs related with energy consumption of used pumps. The optimization problem is solved using genetic algorithm. Implementation of the proposed approach results in reduction of the depth of the thermal shock and achievement of sustainability improvement of the ATAD system.

Ice rink – design of size of water storage tanks with small heat source for ice resurfacing machine

The paper describes a method of design of storage tanks volume for an ice resurfacing machine in ice rink by using heat source with small thermal power (idea of downsizing). The main aim is to minimize investment costs for boiler room (the heat pump water-water). The achieved results show saving of investment costs about 35%. The request is the minimum water temperature at the value of 45°C before each filling process of resurfacing machine. Therefore it is very important to design the storage tanks volume where the water temperature will not be below the 45°C before the each filling an ice resurfacing machine during the hockey match or training. The required volume of storage tanks was calculated at the value of about 2000 litres if there is used the heat source with thermal power 45 kW. The number of storage tanks is given by boiler room dimensions too. In this case 3 storage tanks were designed.

Energetic and Financial Optimization of Solar Heat Industry Process with Parabolic Trough Collectors

The objective of this work is the investigation of a solar heat industry process with parabolic trough solar collectors. The analysis is conducted for the climate conditions of Athens (Greece) and for five load temperature levels (100 °C, 150 °C, 200 °C, 250 °C, and 300 °C). The examined configuration combines parabolic trough solar collectors coupled to a storage tank and an auxiliary heat source for covering the thermal need of 100 kW. The solar thermal system was optimized using the collecting area and the storage tank volume as the optimization variables. There are three different optimization procedures, using different criteria in every case. More specifically, the solar coverage maximization, the net present value maximization, and the payback period minimization are the goals of the three different optimization procedures. Generally, it is found that the payback period is between five and six years, the net present value is between 500–600 k€, and the solar coverage is close to 60%. For the case of the 200 °C temperature level, the optimum design using the net present value criterion indicates 840 m2 of solar collectors coupled to a storage tank of 15.3 m3. The optimization using the solar cover indicates the use of 980 m2 of solar collectors with a tank of 28 m3, while the payback period minimization is found for a 560 m2 collecting area and an 8-m3 storage tank volume. The results of this work can be used for the proper design of solar heat industry process systems with parabolic trough collectors.

Technical assessment, economic viability and investment risk analysis of solar heating/cooling systems in residential buildings in Morocco

This paper focuses on the potential of a solar installation combining air-conditioning, heating and Domestic Hot Water (DHW) production processes intended for mass use in building sector in Morocco. The objective is to measure the relevance of the investment in such systems through a technico-economic assessment and a risk analysis based on classic economic choice criteria. Then, a sensitivity study was conducted to analyze the impact of the major characteristics of a solar plant project (amount of investment, operation cost, solar sunshine, etc.) on the decision-making in various environments to conclude the technical feasibility and economic viability of these systems under Moroccan conditions. Parametric studies including the solar collectors’ technology and field area in addition to the storage tank volume were carried out to design the solar plant and to ensure its optimization in dynamic mode operation. The major finding of this work is that incrementing the collector’s field area to 30 m2 optimizes the thermal efficiency of the solar plant, and the electric booster consumption is reduced. Furthermore, it would be advantageous to use a number of collectors of 14 (a total surface of 22 m2 to satisfy) the cooling, heating and hot water needs over the year since the overall system solar fraction remain above 55% when the optimum parameters are considered. The results indicated also that solar cooling systems in hot climates are an attractive option to increase energy savings and to mitigate CO2 emissions. In addition, the solar contribution has increased from 605 kW h to 705 kW h in winter and summer periods, respectively, while the auxiliary consumption has achieved 1450 kW h, 1875 kW h and 2300 kW h for Agadir, Tangier and Ben Guerir, respectively. However, according to the economic assessment, the high solar plant cost is a main barrier facing their implementation in Morocco. Several recommendations were drawn from the profitability study to identify the sensitive points and to consider avenues for improvement with a view to future industrialization of the combined solar thermal installation in Morocco.

Elimination of dissolved Fe3+ ions from water by electrocoagulation

Electrocoagulation (EC) was applied for elimination of dissolved Fe3+ ions from model contaminated water. Electrochemical experiments were performed using a coagulation set-up with the volume of storage tank of 50 L. To represent inorganic contamination, FeCl3·6H2O was chosen as a model pollutant; its concentration was equal to 50 mg/L. Experiments were carried out by circulating model effluent (1 pass) through the cell at a flow rate (40 L/h) whilst operating the power supply in galvanostatic mode. Dosing concentration was varying by changing the input current between set points and holding for sufficient time for steady state to be reached and for a sample to be collected. The process using the steel electrode reached removal efficiency up to 99%, depending on pH, and proved to be very suitable for elimination of dissolved Fe3+ ions from water. However, electrochemical experiments using the aluminum electrode reached removal efficiency only up to 25%. The different efficiency of two anodes is probably due to lower adsorption capacity of hydrous aluminum oxide for iron ions in comparison to hydrous ferric oxides. Produced nanostructured flocs were subsequently filtered, dried, and characterized by N2 physisorption, X-ray photoelectron spectroscopy, and scanning electron microscopy. Obtained characteristics synchronously demonstrate different tendencies of Al and Fe nanostructured flocs.

OPTIMIZATION OF AN INTEGRAL FLAT PLATE COLLECTOR-STORAGE SYSTEM FOR DOMESTIC SOLAR WATER HEATING IN ADANA

In this paper, the optimum orientation and sizing of a thermosyphon flat plate collector−storage solar water heating system were determined using the typical meteorological year data for Adana, Turkey. The typical meteorological year data for the location was taken from Meteonorm software, and the daily hot water consumption was estimated by utilizing the Rand hot water profile. A transient modeling was carried out for the prediction of a full year system performance through the use of the System Advisor Model simulation program. The effects of the collector area, the storage tank volume, the daily average delivery temperature and the daily hot water consumption on the annual solar fraction were analyzed by the presented simulation model. Results showed that the optimum tilt angle for a due south-facing solar collector is found to be 35.0° for maximizing the annual solar fraction. The collector area and storage tank size greater than 3 m² and 100 L respectively have little effect on the solar utilization.

Optimization of a building integrated solar thermal system with seasonal storage using TRNSYS

In the current work a building integrated solar thermal system with seasonal storage is optimized with the use of TRNSYS modeling software in order to evaluate different integration options of the solar collector array. The model calculates the space heating needs during the heating period as well as the annual domestic hot-water needs of a typical single-family detached home in the city of Thessaloniki, Greece that has been built according to the latest building code. The contribution of the solar system and the thermal load covered by the auxiliary conventional system are determined, for both space heating and domestic hot water, considering the respective simulation periods. The relative solar fractions as well as the combined annual solar fraction are also calculated. A parametric analysis on the impact of various solar collector areas and types, building integration type, as well as the volume of the seasonal storage tank is also presented in order to optimize system design and obtain a seasonal combined solar fraction of at least 39%.

Molten salt power towers operating at 600–650 °C: Salt selection and cost benefits

This analysis examines the potential benefit of adopting the supercritical carbon dioxide (sCO2) Brayton cycle at 600–650 °C compared to the current state-of-the-art power tower operating a steam-Rankine cycle with solar salt at approximately 574 °C. The analysis compares a molten-salt power tower configuration using direct storage of solar salt (60:40 wt% sodium nitrate: potassium nitrate) or single-component nitrate salts at 600 °C or alternative carbonate- or chloride-based salts at 650 °C.The increase in power cycle efficiency offered by the sCO2 Brayton cycle is expected to reduce the size and cost of the solar field required for a given thermal energy input. Power cycle capital cost is expected to decrease compared to the superheated steam-Rankine cycle, based on projections from sCO2 cycle developers. Maximizing the ΔT of the storage system is required for viable deployment of sensible-salt TES. In this regard, the partial-cooling sCO2 cycle is noted as a better option than the recompression sCO2 cycle. In the current analysis it is assumed that a ΔT = 180 K can be achieved with the partial-cooling cycle. Even with ΔT = 180 K, the potential benefits of the sCO2 Brayton cycle are partially or completely offset by increased thermal storage cost, albeit for reasons that differ for the different salts. An approximate 5% reduction in levelized cost of energy (LCOE) is achieved with either solar salt at 600 °C or ternary magnesium chloride salt at 650 °C.The potential of using pure sodium nitrate or potassium nitrate is considered because the cold tank temperature for the sCO2 power cycle is estimated at 420 °C, which would allow use of a salt with a higher melting point than solar salt. Sodium nitrate is the most cost effective, resulting in an overall LCOE reduction of 8.5%; however, sodium nitrate is known to have lower thermal stability than potassium nitrate.The strong influence of salt cost and hot-tank cost on overall economics led to the analysis of single-tank thermocline options. The thermocline design significantly reduces salt inventory (by 50% or more) and in many cases also reduces the tank size versus the hot salt tank of the 2-tank system. It is speculated that integration of encapsulated phase-change material (PCM) in the thermocline could further increase the thermal-storage energy density and reduce storage tank volume. The thermocline cases led to three scenarios with relative LCOE reductions of approximately 10%; however, this must be tempered by possible operational inefficiencies of the thermocline temperature profile.

Modeling, simulation, and optimization of a solar water heating system in different climate regions

To design an effective solar water heating system (SWHS), parameters such as the energy consumption rate, total cost, and climatic region characteristics must be analyzed during the time interval (annual or seasonal) of the predicted use. In this paper, the optimum dimensions of a SWHS were determined using the life cycle cost (LCC) analysis constraint by the 40% solar fraction for the different regions of Turkey for annual and seasonal periods. Particle swarm optimization/Hooke and Jeeves hybrid optimization algorithm was applied. The optimum number of solar collectors and the volume of the hot water storage tank of the SWHS were determined. The optimization process showed that LCC could be reduced for all regions in the range of 3.3%–5.8% in the annual simulation period and 1.8%–4.8% in the period of the summer season simulation. The optimization process carried out in the winter season revealed that the optimization results obtained over different time periods can make a difference in the relations between the optimization parameters. Accordingly, the performance of the SWHS could be improved using a design according to the optimum results obtained at the time interval of the usage. The optimization results obtained in the summer season led to a saving in LCC, while the results obtained in the winter season led to an improvement in the system's thermal performance. Finally, the relative influence of possible operating parameters on an optimum SWHS was investigated through sensitivity analysis.

Theoretical and Experimental Investigation on Performance Improvement of Solar Hot Water System Under Real Weather Conditions at Ho Chi Minh City, Vietnam

This paper presents the results of theoretical and experimental investigation to determine the optimal flow rate of collector loop to improve the performance of a solar hot water system under real weather conditions at Ho Chi Minh City, Vietnam. The optimal flow rate of flat-plate collector loop is researched based on the relationship between the useful heat gain of the flat plate collectors and the electricity consumption of the collector pump. The result of the simulation and experiment shows that the optimal flow rate was determined at the value of 0.132 (kg/s). Besides, the effects of various parameters such as initial water temperature of storage tank, flat plate collector area and volume of storage tank are investigated. Furthermore, the validation of simulation and experiment results of the progress of the water temperature in the storage tank is also evaluated.

The Optimization of Solar Water Heating System Using Hybrid Algorithm (PSO/HJ) for Different Locations of Turkey

In this study, optimum dimensions of Solar Domestic Hot Water System (SDHWS) were determined according to initial capital cost and energy consumption cost in different locations of Turkey. Typical Meteorological Year (TMY) data of 12 different locations which represent climatic characteristics of Turkey were used. Analysis was performed by using Particle Swarm Optimization / Hooke-Jeeves (PSO/HJ) hybrid algorithm which is a part of EnergyPlus®-GenOpt® programs. For each location, optimum number of solar collectors and hot water storage tank volume was determined. Initial investment and energy consumption costs decreased 6.1% for Gaziantep whereas solar fraction increased 42.8% for Ankara. In average, 4.5% decrease in initial investment and energy costs and 35.4% increase in solar fraction were obtained.

Optimal design of PCM thermal storage tank and its application for winter available open-air swimming pool

This paper presents a general procedure to optimize the design of a PCM storage tank, including the specification of design objectives, the identification of decision variables (for optimization), the construction of computer simulation platform and the final decision making. The general procedure was demonstrated by applying it to an open-air swimming pool, where the design objective was to minimize the volume of the PCM storage tank when it was required to enable heat storing to maintain the water temperature of an open-air swimming pool inside the thermal comfortable range during its open period in winter season. After identifying decision variables, a computer simulation platform was developed using TRNSYS and MATLAB to investigate the effects of the decision variables on the volume of the PCM storage tank. Case studies show that the proposed optimization is able to efficiently reduce the volume of the PCM storage tank without sacrificing the thermal storage capacity. Therefore, this study provides useful guidelines to optimize the design of a PCM storage tank.

Daily performance of parabolic trough solar collectors

Parabolic trough collector (PTC) is the most mature concentrating technology which is used in a great variety of thermal applications. In this study, the daily performance of a PTC is investigated for all the year period. The module of Eurotrough parabolic trough collector is examined with various storage tanks from 3 m3 to 15 m3 and the collector performance is investigated in energetic and exergetic terms. An Input/Output method is applied for the daily evaluation of the solar thermal system, something innovative for concentrating solar collectors. According to the final results, different storage tank volumes lead to similar thermal outputs but to extremely different exergetic outputs because of the high dependence of the mean storage tank temperature with the storage tank volume. For the storage tank of 9 m3, the mean thermal efficiencies in December and in June are found to be 37.1% and 68.7% respectively, while the mean exergetic efficiencies 2.0% and 8.5% respectively. Moreover, it is proved that the Input/Output performance method in concentrating collectors has to take into consideration the solar incident angle at solar noon in order high accuracy to be achieved.