Water Heater Tank Research Articles

Enhancing Solar Water Heater Performance Using Phase Change Materials and Modified Encapsulation Geometry

ABSTRACTSolar energy's abundant availability in India makes it a potential solution to meet increasing energy needs without harming environment. Solar water heating (SWH) systems are effective in converting solar radiation into heat for domestic and industrial applications. However, their inability to provide hot water during nighttime or off‐sunshine hours due to the intermittent nature of solar energy presents a challenge. Thermal energy storage, particularly using phase change materials (PCMs), has emerged as a solution. In this study, spherical ball‐type encapsulated PCM, specifically RT60, was incorporated into a solar water heater tank under variable atmospheric conditions. The PCM stores excess energy during daylight and releases it when the water temperature drops below the PCM's melting point. The results reveal a significant reduction in the temperature drop of water from 4.5°C to 1.4°C when utilizing PCM compared to conventional storage water tanks without PCM. Additionally, energy storage capacity is enhanced by 5.13% with PCM incorporation. Furthermore, modifying the encapsulation geometry to a rectangular shape enhances heat transfer and reduces temperature drop even further to 0.9°C, making it a promising approach to improving SWH system performance. This study highlights the possibility of enhancing encapsulation shape and applying PCM to enhance SWH system performance. The results highlight the possibility of increasing solar thermal systems' energy efficiency and usefulness, which will support sustainable energy sources.

Review on Smart Water Heater Power Saver Using Detectors

Since water heating is a basic task of our day- to- day life, it has been turned into efficient technology through water geyser system. Water geyser is used for thermodynamically hotting water above its normal temperature. Its procedure incorporates in bathing, washing, cooking & numerous where. So to corroborate the public demand, the crucial challenge is to make the system more cheap but effective, handy but less incorrect. To hold its performance as well as cost, we need to design such a system that will give us with exactly how we anticipate it to be. Although traditional electric storehouse tank water heaters( ESTWHs) are the most constantly used systems in the world, they're known to be among the loftiest energy consumers, due to their inefficiency in converting electrical energy to thermal energy. These systems have grown decreasingly hostile to consumers, as power prices have raised. thus, the need to reduce energy consumption of hot water product, while maintaining the druggies ’ thermal comfort position, has led to the development of further energy-effective technologies. In this paper, a review of renewable energy water heating systems i.e. solar panel, as well as the background literature of the studies on these systems. In this paper electric heater is safer, affordable, and effective and is the most constantly chosen option. In this paper, we proposed a system, which can give a way to maintain a moderate temperature and save energy. Representing spring heater rather of a rally geyser, we'd set a specific temperature range on it. After switching the system on for the first time, if the temperature of the water went below the preset range, the heater bus- rebooted and took the water into that range of heat. However, the whole system might be turned off regarding the possibilities that no consumption of water was going on, If the heater was on and sat idle for a veritably long time.

Heat pump water heater enhanced with phase change materials thermal energy storage: Modeling study

A promising solution to improve the first hour rating (FHR) of a heat pump water heater (HPWH) involves employing a secondary tank which contains phase change material (PCM) capsules. To better understand the influence of PCM thermal storage on the HPWH operational performance, a dynamic model was developed to simulate and analyze the behavior of a newly developed HPWH technology that incorporates PCM storage into a standard HPWH to optimize key parameters such as the uniform energy factor and FHR. Mathematical models of several key components of the proposed HPWH-PCM integrated thermal energy storage (TES) system, e.g., water heater tank, PCM TES tank, evaporator, compressor, and expansion valve, have been elaborated. Also, a model-based control co-simulation platform was developed to integrate a embed PCM storage HPWH dynamic model with a control model for better supporting control design, analysis, verification, and validation. The model accuracy has been validated through comparing simulation results with lab test results, with a mean average percentage error of <5.5% for most of the selected performance variables. In addition, using the developed co-simulation platform, the demand response control strategy was studied to evaluate the load flexibility of the combined HPWH-PCM storage system by shifting system power usage to outside of the 3.5 h peak load period.

Modeling the temperature regime of the heat accumulator

In the article, a mathematical model of the temperature regime (charge and discharge) is developed based on the balance equation of the water tank heat accumulator. In the development of the mathematical model, the results of the temperature regime are presented, taking into account different volumes of the water tank accumulator (40, 60, 80, and 120 m3) and other water consumptions (2, 4, 10, and 15 m3/h). When creating the balance equation, solar energy and thermal energy from the biogas boiler were taken into account, and the heat storage efficiency of the water tank accumulator was calculated.

Trends in residential sustainability measures in the state of Victoria

Buildings require a significant quantity of energy and water during their operation. Solar water heaters and rainwater tanks have become increasingly common to reduce the demand for fossil-fuel based energy and mains water within buildings. Since 2006, the Victorian Building Authority has required either a rainwater tank or solar water heater to be installed in any new house built in Victoria, Australia. This research analyses the trend in adoption of these two systems using data from building permits issued from 2006 to 2019. This shows that despite an initial preference for rainwater tanks, solar water heaters have been the preferred choice. This preference was found to be greatest for projects costing from $200k-$600k and for allotment areas smaller than 500 m2. Preference for rainwater tanks tended to increase in line with an increase in project cost and allotment area, and this preference was found to be most common in metropolitan areas. This study provides insight into the opportunities for further adoption of solar water heaters and rainwater tanks, including using information at the LGA level to develop specific business opportunities or to inform policy, such as alternative water efficiency solutions for households where allotment area may limit rainwater tank adoption.

Optimal energy management of a solar-assisted heat pump water heating system with a storage system

Water heating is the fourth largest energy consumer in the commercial building sector, accounting for >40 % of the energy consumed in South Africa. Traditional electric storage tank water heaters (ESTWHs) have been the most frequently used systems in the past, owing to their low electricity costs and implementation. It was low enough at that time that energy costs were not considered. These systems have grown increasingly hostile to consumers as power prices have risen, particularly to the undesirable high morning and afternoon peaks.The indirect-expansion solar-assisted heat pump water heater (IDX-SAHPWH), for the commercial sector, to reduce energy consumption of hot water production while maintaining the users' thermal comfort level, has been proposed in this paper. The system is operated under an optimal energy control scheme, integrated with the load shifting by time-of-use (TOU) pricing plan. The comparison of the performance of the proposed optimally controlled system and the electric storage tank water heater (ESTWH) was performed through the simulation approach using the Solving Constraint Integer Programs (SCIP) solver, in the MATLAB interface optimization toolbox. The simulations reveal that the proposed system operates during off-peak hours, when power prices are lower, as compared to ESTWH system.The techno-economic analysis was conducted and presented for a project lifespan of 20 years. The proposed optimally controlled system demonstrates the cost savings obtained from the winter and summer seasons, as well as annual, as 76.0 %, 75.6 % and 75.8 %, respectively. The break-even point of the project is during the 9th month of the first year of the project, with a possible savings of 71.5 % at the end of the project's lifetime.

A review of solar and air-source renewable water heating systems, under the energy management scheme

Although traditional electric storage tank water heaters (ESTWHs) are the most frequently used systems in the world, they are known to be among the highest energy consumers, due to their inefficiency in converting electrical energy to thermal energy. These systems have grown increasingly hostile to consumers, as power prices have risen. Therefore, the need to reduce energy consumption of hot water production, while maintaining the users’ thermal comfort level, has led to the development of more energy-efficient technologies. In this paper, a review of renewable energy water heating systems, particularly air-source heat pump water heaters (ASHPWHs), solar water heaters (SWHs) and solar-assisted heat pump water heaters (SAHPWHs), as well as the background literature of the studies on these systems, carried out in South Africa, under the energy management schemes, is presented.

A Drying system for Rhizoma et Radix Baphicacanthis Cusiae Based on multi-source coupling and efficient energy storag

The traditional Chinese Herbal Medicine Rhizoma et Radix Baphicacanthis Cusiae mostly grows in Southwest China. However, due to the lack of technology, the key drying process in the production of Rhizoma et Radix Baphicacanthis Cusiae has the problems of low efficiency, long time and uneven quality. The paper designed a drying system of Rhizoma et Radix Baphicacanthis Cusiae based on multi-source coupling and efficient energy storage by investigating the production of Rhizoma et Radix Baphicacanthis Cusiae in southwest China and studying the natural effects of geographical advantages and light conditions in the region. The main body of the system is composed of a two-position water tank heat circulation system, a hemispherical Fresnel lens array, an air source heat pump, a dehumidification and waste heat recovery device, a temperature and humidity sensor, and a heat exchange tube group. The drying system can better meet the drying needs of Chinese herbal medicine Rhizoma et Radix Baphicacanthis Cusiae. It has the advantages of high efficiency, energy conservation and environmental protection, stable operation, and can independently adjust according to the drying temperature. It has strong practicability. While saving energy, it saves high drying cost for farmers, and meets the special requirements of building intelligent agriculture and enriching rural economic business forms.

Effectiveness of capsules installation containing paraffin wax in a solar water heater

The encapsulation technique is one way to use latent heat storage material in a solar water heater tank. In this technique, several capsules may be arranged in the tank. In this study, the capsules were installed along the cross-section of the tank. There has been no discussion of which part of the capsule position has optimal heat energy with a capsule arrangement. Proper placement of the capsule arrangement can result in optimal thermal energy storage in the tank. This study aimed to investigate the effectiveness of installing capsules in a tank with different positions in terms of thermal energy storage. The study used an active solar water heater. The 24 capsules containing paraffin wax were arranged in a tank. The solar simulator was used as a heat source for the collector, and it was set at 1000 W/m2. The flow rate of water was 2 liters/minute. During the charging process, the water and paraffin wax temperature was recorded. The temperature evolution of water and paraffin wax obtained were used to analyze the thermal energy content. The results showed that the average heating rate for water and paraffin wax was 0.246 °C/min and 0.254 °C/min, respectively, so the capsule arrangement served as a suitable heat exchanger. The capsules installed at the top had an average heating rate increase of 111.4% compared to those at the bottom. Therefore, mounting the capsule at the top of the tank was more effective than placing it at the bottom.

A field study of combo heating systems in Canadian single-family buildings

This study presents a field study of the performance of three multi-zone gas-fired comboheating systems that provide space heating and domestic hot water in three new single-family houses in the Greater Toronto Area in the Province of Ontario, Canada. Two systems are composed of a gas-fired condensing tankless water heater integrated with a smart air handling unit, while the third system is composed of a gas-fired condensing combi boiler integrated with a smart air handling unit. The performance of the three combo heating systems was monitored, analyzed and evaluated over one heating season. The gas consumption of the three systems were compared with traditional gas-fired heating systems (composed of forced-air gas furnace and gas storage tank water heater). Results showed that combo heating systems tested in this study are reliable, met the peak space heating load, improved the indoor thermal comfort by providing two independently controlled temperature zones and achieved significant gas savings compared to traditional natural gas heating systems. The annual gas consumption and greenhouse gas emissions of the combo heating systems tested in this study are less than the traditional gas-fired heating system (forced-air gas furnace and gas storage tank water heater) by up to 29%.

Research on Designing an Industrial Product-Service System with Uncertain Customer Demands

The industrial product-service system (iPSS) is a kind of system engineering methodology, integration scheme, and business model to realize service value by adding intangible services in the whole life cycle. However, the design of the system involves many difficulties such as uncertain customer demands, strong subjectivity of the experience design, and long debugging times. Methods for solving upper problems are therefore essential. This paper presents a design model that integrates an improved affinity propagation (AP) clustering algorithm, quality function development (QFD), and axiomatic design (AD). The entire process of designing an iPSS can be split into three steps. First, uncertain customer demands is determined and standardized. Second, the functions of the product-service system are investigated. Finally, the structures of the system are determined. This paper examines the example of the control service of an iPSS for a water heater tank capping press. An improved AP clustering algorithm is used to determine standardized customer demands, the proposed QFD, and an AD integration model to initially establish a mapping between the customer demands domain and the function domain and clarify the design focus. Next, a QFD- and AD-integrated model is constructed to establish a mapping between the function domain and the structure domain and optimize the control scheme through the quality of its risk prediction. Finally the paper verifies that the upper process and methods can guide the design process effectively in production applications.

Energy analysis of heat pump water heaters coupled with air-based solar thermal collectors in Canada and the United States

Heat pump water heaters (HPWHs) operate with two to three times the efficiency of electric water heaters, and over three times the efficiency of natural gas water heaters; however, this benefit is accompanied by a secondary space cooling effect that increases space heating costs. To mitigate this, HPWHs may be coupled with solar thermal collectors which preheat inlet air. The objective of this study was to compare the energy performance of HPWHs and solar-assisted HPWHs (SAHPWHs) across Canada and the United States, to determine where the SAHPWH could offset the space heating increase of HPWHs. This was done using an empirical model, with different modelling methods and assumptions that were assessed and compared. It was found that the SAHPWH could fully mitigate the space heating increase throughout winter, while decreasing the space heating load by 1–3%, and during the cooling season, decreasing the space cooling load by 7–15% in all climates studied. This research indicates that HPWHs and SAHPWHs have potential to lead a higher efficiency future, by reducing energy consumption for water heating beyond what is presently achievable with electric and natural gas storage tank water heaters.

Hydrodynamic behavior of wrapped coil water heater tank

A numerical investigation using computational fluid dynamics (CFD) has been carried out to analyze the thermal behavior of a water tank integrated to a heat pump water heating system (HPWH). The heat pump condenser is a long coil wrapped around the water tank and insulated from outside from which heat is transferred from the heat pump cycle into the water stored inside the tank. The simulated water tank has a capacity of about 170 L with the charging inlet located at the bottom segment of the tank and the discharging outlet located at the top segment of the tank like commercially available water heaters. The tank was simulated during charging/discharging process with isothermal boundary condition at the tank wall to represent the majority of the process for refrigerant condensation inside the heat pump condenser (excluding superheated and sub-cooled section). Three flow rates were selected to represent low, medium and high flow pattern. Both mean and turbulent flow properties were calculated and analyzed. Heat transfer mechanisms inside the tank are quantified by calculating Richardson and Péclet numbers to show the relative contribution of driving forces. The calculations show that advection is dominant over diffusion. Mixing factor is calculated and presented. It is found that the rate of increase of mixing is nonlinear with the increase in flow rate. Mixing increased by a factor of four when the flow rate increased by a factor of two.

Cleaner production of combined cooling, heating, power and water for isolated buildings with an innovative hybrid (solar, wind and LPG fuel) system

An innovative hybrid (renewable and non-renewable) energy system for cleaner production of combined cooling, heating, power and fresh water of isolated (not connected to electricity, gas and water grids) buildings in an Island is proposed here. The system consists of photovoltaic (PV) panels, wind turbines, batteries and micro-CHP units to provide electrical demand. The hybrid system also contained evacuated tube (ET) collectors, micro-CHP units, gas water heater and hot water storage tanks (HWST) for supplying heating demand. An electrical chiller also provides cooling demand. A reverse osmosis (RO) system is used for the production of desalinated water. To estimate the chiller and RO system electricity consumption during each operating point Artificial Neural Network (ANN) is applied. Results show that the innovative combined ANN and PSO optimizing methods decreased the run time for about 10%. Furthermore the effect of using excess heat in preheating of RO feedwater which reduces RO electricity consumption is investigated. RO feed water preheating decreased the annual RO electricity consumption for 733 kWh/year (4.95%). Modeling and optimizing the proposed novel hybrid system depict that by optimum selection of hybrid system equipment, 43.3% of electrical load and 43.6% of heating load are provided by renewable systems and the rest are generated by LPG fuel. This shows that 67.3% saving in fossil fuel consumption and about 73 361 kg/year (67% compared to that for the traditional system) reduction in CO2 production are reached. Change in optimum selected equipment with change in fuel (LPG) cost and ambient conditions are also investigated.

Design of a partially premixed burner for biogas-fired wall-mounted boiler

Abstract Biogas is deemed as one of the most promising renewable fuels emerging in the past several decades. At present, biogas is mainly applied to cooking for substituting fossil fuels. However, biogas is rarely reported to be used for space heating. In this paper, we designed a biogas-fired partially premixed burner for gas-fired wall-mounted boilers, which has the heat input of 25 kW and can be used for space heating and water heater tank heating. The reference gas was assumed as 60% of methane (CH4) and 40% of CO2, and the burner port area was designed as 4744.5 mm2 according to the calculation. Then, experiments were conducted to study the performance of this burner. Jet diameters were modified in order to investigate their effects on heat input, primary air ratio and flame stability of the burner. The results indicate that the burner shows superior performance when the jet diameter is 2.0 mm. Meanwhile, the primary air ratio (${\alpha}^{\prime }$) satisfies the design requirement. Moreover, a gas-fired wall-mounted boiler with this burner was examined to investigate the influence of different biogas composition on exhaust emissions and thermal efficiency. The results show that the concentration of CO in the flue gas meets the national standard when CH4 varied from 40% to 60% in the biogas. However, the thermal efficiency of the biogas-fired wall-mounted boiler reduces greatly with the increase of CH4 percentage.

Optimal energy management and economic analysis of a grid-connected hybrid solar water heating system: A case of Bloemfontein, South Africa

In this paper, the optimal energy management of a hybrid solar electric water heater is presented. A typical medium density household is considered. Actual historic exogenous data, obtained from a weather station in the considered area is used as input for the established model.The aim is to evaluate the energy and cost saving potential of the system, that may be achieved under time-based pricing, while maintaining a comfortable thermal level of the hot water user.Comparisons between the operation of a thermostatically controlled traditional electric storage tank water heater and the hybrid solar electric water heater, offered an energy saving of 75.8% in the winter and 51.5% during the summer period.A life cycle cost (LCC) analysis is presented, where the project lifetime is taken over 20 years. The LCC analysis of the hybrid system demonstrates a 44% saving in overall cost, as compared to a traditional water heating system. Simulation results conclude that the break-even point for the evaluated system was at R10 870 in 3.3 years, under the evaluated time-based pricing structure.

A review of water heating technologies: An application to the South African context

Abstract The process of water heating consumes enormous amounts of energy. South African households may see up to 40% of their total energy be allotted to the heating of water. The implementation of energy efficient or renewable energy source technologies, for the main purpose of heating water, may assist in reducing the magnitude of the energy crisis that South Africans are facing daily. This will, in turn, reduce energy consumption and costs, so that the energy price hikes do not affect the consumers as severely as it would otherwise. The purpose of this paper is to provide a survey of the most frequently used domestic water heating technologies. The paper aims to critically analyse and summarize recent advancements made in renewable and non-renewable water heating technologies, particularly in the South African case. These technologies include the electric storage tank water heater, solar water heaters (passive and active circulation), heat pump water heater, geothermal water heating, photovoltaic-thermal water heater, gas-fired tankless water heater, biomass water heater and oil-fired water heater. Substantial research works and other academic studies focusing on efficiency improvement, optimal design and control, were consulted and categorized in terms of contributions, focus and respective technologies. The key findings of the review conducted on the various water heating technologies are discussed and organized, based on the advantages, drawbacks, approximate initial investment, average life expectancy and payback period. The results of this survey identify gaps in existing research. The aim is to propose a new perspective on the importance of energy efficient hybrid water heating systems and the cost savings they might offer.

Numerical study of an external device for the improvement of the thermal stratification in hot water storage tanks

In this work, we study the operation of a water heater storage tank using CFD modelling and analyse its limitations in order to propose a redesign that improves its characteristics. The study method is based on calculating the main variables that affect the thermal performance using the finite volume method. With this method, the Navier-Stokes equations are applied to calculate the internal movements of the fluid and its heat exchange with the coil. A determining factor for the operation of a water heater tank is natural convection, which is solved by means of the Boussinesq approximation. Different reservoir simulations are carried out in continuous operation mode (stationary) and in heating mode (transient). In both cases, the results show very homogeneous heating, which means poor temperature stratification. As an alternative for improvement, a redesign of the system is proposed by means of an auxiliary tank where the heating coil is located, which injects the hot water, at different heights, into the main tank. Several simulations of this redesign are carried out with different configurations in order to achieve better temperature stratification, reduce the heating time and maintain the outlet temperature of the domestic hot water (DHW) between 45 and 60 °C. As a result, the redesign significantly improves the stratification of temperatures and reduces the heating time necessary to obtain a DHW temperature of 45 °C from 45 to 8 min.

Numerical study of the thermal behaviour of a water heater tank with a corrugated coil

This work proposes a method based on CFD techniques for the study of thermal water heater tanks. The method is based on using the Navier-Stokes equations to calculate the internal movements of the fluid and the transport of energy through the flow. The Boussinesq approximation is applied to solve the fluid movements that occur by natural convection, which represents a great computational savings compared to other methods based on variable densities with very short time steps. Because the tank has a corrugated coil whose mesh poses major computational challenges, a fitting method is used to calculate the heat transfer of the corrugated surface in a smooth coil. The model is applied to a tank with 150 L of water, which is heated by a heat exchanger in the form of an outer jacket. The heat accumulated in the tank is exchanged with the drinking water by means of a corrugated coil located inside the tank. The model is tested by simulating several steady-state continuous consumption experiments and by conducting a transient test of heating and subsequent cooling. For the comparison of results, the data used include the flow rates through the water jacket and the inner coil, the inlet and outlet temperatures of these flows and various temperatures recorded by thermocouples located inside the tank at different heights. The results obtained from the simulations are reasonably close to the experimental observations. The experimental data show an aggressive temperature increase in all thermocouples, except the highest, at the beginning of heating and a softer increase at the end. A similar behavior occurs during cooling, aggressive at the beginning and softer as time progresses. This behavior is also obtained in the model predictions, especially in the lower thermocouples. The greatest discrepancy is found for the highest thermocouple during cooling. The experimental tests show a noticeably slower cooling than the model predictions.

Experimental performance evaluation and parametric study of a solar-ground source heat pump system operated in heating modes

The dual heat source coupling modes of solar-ground source heat pump system (SGSHPS) directly determine its operation characteristics. In this paper, the thermal performance of a SGSHPS operated in different dual heat source coupling modes were studied experimentally. The unit COP, solar collecting efficiency and inlet and outlet temperatures of GHE were tested for various modes. The results show that for the combination operation mode, solar and ground heat source are dynamically coupled by the water tank and plate heat exchanger, and the average unit COP and collecting efficiency are 3.61 and 51.5%, respectively. For the water tank heat storage mode, the inlet water temperature of evaporator in the daytime stop mode of GSHP is 1.85 °C higher than daytime operation mode of GSHP, and the average unit COP and collecting efficiency are respectively 3.43 and 34.8%, 3.91and 34.9% for the daytime stop mode of GSHP and daytime operation mode of GSHP. For the ground heat storage mode, the ground temperature can be improved effectively for ground continuous heat storage mode and the outlet temperature of GHE can be increased significantly for ground intermittent heat storage mode. The average unit COP and collecting efficiency are 3.65 and 47.9%, 3.8 and 41.5% for the ground intermittent and continuous heat storage mode, respectively. A TRNSYS dynamical simulation model of the SGSHPS was established to explore the influences of key parameters on the system performance. The results indicate that the collector area and GHE number have evident influences on the system efficiency, but the impact of water tank volume is very small. The suitable collector area and GHE number are found to be 80 m2 and 9, respectively, and the water tank volume should be set as small as possible with the permission of actual conditions.