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The rising share of renewable energies leads to increased fluctuations in electrical power supply. One possibility to shift the surplus energy based on demand is a Carnot battery (CB). A CB uses a heat pump or resistance heater to convert and store thermal energy into electrical energy. Later, the stored thermal energy is converted back into electrical energy using a heat engine. This study investigates a CB with a two-zone tank for thermal energy storage. A transcritical process with CO 2 is applied for charging, while discharging employs a transcritical process with CO 2 and six refrigerants operating in a subcritical process. The transcritical process with CO 2 and the four most promising subcritical processes are compared regarding round trip efficiency and levelized cost of electricity (LCOE) depending on the pinch points 5 K and 1 K in the heat exchangers. Additionally, the technology readiness level (TRL) is determined for these configurations. The results show round-trip efficiencies between 11.3% and 33.5% and LCOEs ranging from EUR 0.95 (kWh) − 1 to EUR 2.09 (kWh) − 1 for the considered concepts with TRLs of up to six. [ABSTRACT FROM AUTHOR]

Due to aging infrastructure, frequent wastewater network overflows, and potential charges for stormwater disposal, there is a need to find alternative approaches to stormwater management. Rain gardens and rainwater harvesting systems are widely used in local areas such as private homes, small businesses, and parking lots. Therefore, the aim of this study was to conduct an economic analysis of two alternative solutions -- a storage tank with water reuse and a rain garden. The cost-benefit analysis was based on an evaluation of the effectiveness of each approach in reducing stormwater runoff volume and decreasing stormwater disposal fees in the wastewater network. The precipitation regime used for the calculations was selected based on data from 2014 to 2023 for the Kyiv. In the study, technical and economic aspects were considered as key factors in the decision-making process. The results of the economic sustainability analysis of both options using an example of an impermeable surface showed that both systems have an effective service life of approximately two years. The storage tank is an effective solution, reducing stormwater overflows and allowing the collected water to be reused for various purposes. However, the costs of construction and maintenance of the tank exceed the savings on stormwater disposal fees to the sewer system by almost twice, therefore the project is not economically viable in the initial period. The implementation of a rain garden design to reduce stormwater disposal fees to the wastewater network is the most cost-effective solution. Assuming that the effective use period of a rain garden design is 8-10 years, the accumulated savings on tariffs can range from €606.8 to €848.2. The introduction of financial incentives will help promote the implementation of alternative stormwater control solutions, leading to a range of environmental and economic benefits, such as reducing the impact of stormwater on the environment, protecting water resources, and potential savings in the construction and management of stormwater systems [ABSTRACT FROM AUTHOR]

Mixing and renewal processes are crucial for maintaining adequate drinking water quality in storage tanks. This paper studies the influence of baffle structures and of fill-and-draw cycles on water mixing and renewal in rectangular cross-section tanks through laboratory tracer tests carried out in two small-scale tanks (with and without baffles) and compares with results from a full-scale test. This study shows that the use of baffles inhibits water mixing and keeps older water pockets in small recirculation zones, though baffles allow faster water renewal than in open tanks for lower flow rates. High water volume variation in fill-and-draw cycles (between 50% to 80%) promotes water renewal, independently of the tank configuration (i.e. cross-section and the existence of baffles). Despite the existing baffle structure in the full-scale rectangular tank with 20% water volume variation, the high flow rates allowed a rapid renewal of the stored water. [ABSTRACT FROM AUTHOR]

Urban villages are unique residential neighborhoods in urban areas in China. Roof tanks are their main form of water supply, and water quality deterioration might occur in this system because of poor hygienic conditions and maintenance. In this study, water samples were seasonally collected from an urban village to investigate the influence of roof tanks as an additional water storage device on the variation in the microbial community structure and pathogenic gene markers. Water stagnation in the roof tank induced significant decreases in chlorine (p < 0.05), residual chlorine was as low as 0.02 mg/L in spring. Propidium monoazide (PMA)-qPCR revealed a one-magnitude higher level of total viable bacterial concentration in roof tank water samples (2.14 ± 1.81 × 105 gene copies/mL) than that in input water samples (3.57 ± 2.90 × 104 gene copies/mL, p < 0.05), especially in spring and summer. In addition, pathogenic fungi, Mycobacterium spp., and Legionella spp. were frequently detected in the roof tanks. Terminal users might be exposed to higher microbial risk induced by high abundance of Legionella gene marker. Spearman's rank correlation and redundancy analysis showed that residual chlorine was the driving force that promoted bacterial colonization and shaped the microbial community. It is worth noted that the sediment in the pipe will be agitated when the water supply is restored after the water outages, which can trigger an increase in turbidity and bacterial biomass. Overall, the findings provide practical suggestions for controlling microbiological health risks in roof tanks in urban villages. [Display omitted] [ABSTRACT FROM AUTHOR]

The rising share of renewable energies leads to increased fluctuations in electrical power supply. One possibility to shift the surplus energy based on demand is a Carnot battery (CB). A CB uses a heat pump or resistance heater to convert and store thermal energy into electrical energy. Later, the stored thermal energy is converted back into electrical energy using a heat engine. This study investigates a CB with a two-zone tank for thermal energy storage. A transcritical process with CO2 is applied for charging, while discharging employs a transcritical process with CO2 and six refrigerants operating in a subcritical process. The transcritical process with CO2 and the four most promising subcritical processes are compared regarding round trip efficiency and levelized cost of electricity (LCOE) depending on the pinch points 5 K and 1 K in the heat exchangers. Additionally, the technology readiness level (TRL) is determined for these configurations. The results show round-trip efficiencies between 11.3% and 33.5% and LCOEs ranging from EUR 0.95 (kWh)−1 to EUR 2.09 (kWh)−1 for the considered concepts with TRLs of up to six.

Studies on the mixing of water storage tanks typically consider vertically oriented nozzles, however, not much consideration was given for horizontally oriented nozzles. This paper aims to employ computational fluid dynamics (CFD) to study the influence of horizontal nozzle configurations on the mixing within a typical circular water storage tank. The impact of the outlet locations and water depths on mixing time was also investigated. The results from the numerical simulations show that nozzle configuration with horizontal distance between the sets of nozzles of 0.71 tank diameters apart performed the best. An outlet located in the center of the circular storage tank encourages near-floor lateral movement of fluid and improved the velocity uniformity across the water column. The water depth was found to have a non-monotonic relationship with the mixing time and the depth to diameter ratio of 0.4 provides the best mixing in the studied tank with nozzles. [ABSTRACT FROM AUTHOR]

Phase change material (PCM) water tanks have a major influence on the efficiency improvement of solar energy systems. This article discusses the effects of PCM under various inlets in a tank based on related research. So as to research the performance of the water storage tank, this paper built a set of water tank experimental systems using sodium acetate trihydrate. The thermal characteristics of two different water tanks were analyzed at 2, 6 and 10 L/min when the inlet temperature was 20 °C and the initial high temperature was 80 °C. The test results indicate that adding PCMs helps to provide an extra 1.4% of stored heat, prolong the hot water outlet time, and has a better thermal stratification, compared with ordinary water tanks. However, PCMs do not give off heat quickly at high flow rates. Besides the exergy efficiency (EE) gradually decreasing, the MIX number first decreases and then increases; the fill efficiency (FE) has the opposite trend with the flow increasing. FE has a max of 0.905 at 6 L/min. [ABSTRACT FROM AUTHOR]

With the gradual increase of the amount of sewage produced by the gas well, the corrosion risk of the sewage treatment device in a gas gathering station in the west gradually increases. Taking the on-site sewage as the research object, the influence of different factors on the corrosion rate of Q235 steel sheet of water storage tank is investigated by using the weight loss method, and the corrosion protection measures are put forward. The experimental results show that with the gradual increase of salinity, dissolved oxygen content, carbon dioxide content, sulfide content and temperature of sewage, the corrosion rate of sewage to Q235 steel sheet shows a gradual increase trend, while with the gradual increase of pH value of sewage, the corrosion rate of sewage to Q235 steel sheet shows a gradual decrease trend. Epoxy resin coating can effectively reduce the corrosion rate of sewage on Q235 steel of water storage tank, and the greater the coating thickness, the better the anti-corrosion effect. The higher the dosage of HS-1 corrosion inhibitor is recommended, the better the corrosion inhibition performance of steel can be reduced. [ABSTRACT FROM AUTHOR]

The mixing performance of a water storage tank is important to ensure good drinking water quality in a distribution system. A tracer study is a commonly used approach for mixing performance evaluation but has limitations, such as limited sampling points and inability to be applied to the full scale at design stage. In practice, mixing time is usually estimated by the tracer curve measured by a probe sensor in a physical tracer study. However, the probe tracer concentration curve can be affected by many factors in the tracer release approach (e.g., instantaneous pouring or quill injecting), such as pouring volume, vertical penetration, and injecting time, making the estimated mixing time inaccurate. Coefficient of variation (CoV) decay curve is an alternative for determining mixing time. In this study, computational fluid dynamics (CFD) models were developed to study mixing in a cylindrical water tank. Mixing times were estimated from both probe tracer curve and CoV decay curve. Results show that the mixing time estimated from a probe tracer curve only represents local mixing, while that estimated from a CoV decay curve is a more appropriate index for global mixing, suggesting that the CoV decay curve should be used for mixing performance analysis in a water tank. HIGHLIGHTS Compared two approaches for estimating mixing time in water storage tanks.; Probe tracer curve predicts inaccurate mixing time and highly depends on tracer release method.; CoV decay curve predicts accurate mixing time and less dependent on tracer release method.; CoV decay curve is suggested for both physical and numerical mixing analysis of water tank.;

Rainwater harvesting (RWH) is one of the most important means of water conservation today. Although there is tremendous emphasis on the implementation of this versatile technology at various levels, many of us are unaware of its significance and its consequences. This study examines the perception and awareness of people in the state of Tamil Nadu, India, of the RWH system through a questionnaire survey. The survey was conducted to infer basic information on rainwater harvesting features, water quality and conservation, economics of implementation and financial support. The results show that there is an increasing need to promote the usage of harvested rainwater for domestic purposes rather than direct groundwater recharge. The potential risks in the reliable supply of available water sources demand large-scale implementation of RWH especially in apartments. Fewer people are aware of the technical details of operation and maintenance of the RWH system (22.2%) while more people are aware of the general layout of the system (50.5%). Longer experience in using RWH systems (for more than two years) builds confidence in using them for consumptive uses compared with the response from recent adopters. This also demonstrates the scope for a radical change in the perception of water quality by continuous awareness and financial incentives. HIGHLIGHTS Structured questionnaire survey to realise the awareness of people about improving rainwater harvesting (RWH) infrastructure.; Suspicion of reliability in available water resources promotes early adoption of RWH systems.; Experience with RWH makes changes in people's perception towards ensuring water quality and proper usage.; Major hurdles in RWH: promotion through demonstration, access to financial incentives and implementation of groundwater recharge.;

With the expansion of installed capacity of new energy power generation, the thermal power market has been severely squeezed. To meet the needs of grid flexibility, thermal power plants are required to undertake the task of deep peak shaving. Circulating fluidized bed units can be used without shutdown. It takes a supercritical 350MW circulating fluidized bed unit in a power plant in Shanxi Province as the research object. Two kinds of deep peak shaving methods of supercritical circulating fluidized bed unit's typical steam-water systems were analyzed. Some problems that might be encountered during operation were analyzed. Corresponding prevention and control measures were provided. Finally, the analysis shows that the supercritical circulating fluidized bed unit can use two typical steam-water systems to achieve full load deep peak shaving. The investment of adding boiler water circulating pump system is large, and the operation is complex. The investment of adding water storage tank to deaerator pipeline is small, and the operation is simple. However, when the boiler water circulating pump system is added to participate in full load deep peak shaving, the stability of each system is better.

Water circulation in storage tanks significantly impacts water quality in distribution networks since old water tends to have low residual chlorine concentrations that are insufficient to neutralize microbial regeneration. Their large capacity and long residence times result in uneven mixing, which can accelerate the disinfectant decay and the formation of potentially carcinogenic disinfection by-products. The phenomenon is strongly related to the tank inflow conditions, since there are no active mixing devices. This paper presents a comprehensive analysis of the flow dynamics in circular storage tanks using a three-dimensional computational fluid dynamics model. The main motivation is that the inflow—which mixing processes rely on—strongly influences the circulations. The numerical analysis provided includes a thorough investigation of interest in understanding flow dynamics for two inflow configurations: (i) the plunging jet modelling and comparison with published experimental data and (ii) the submerged jet as an improvement measurement for these storage tanks. [ABSTRACT FROM AUTHOR]

Phase change material (PCM) water tanks have a major influence on the efficiency improvement of solar energy systems. This article discusses the effects of PCM under various inlets in a tank based on related research. So as to research the performance of the water storage tank, this paper built a set of water tank experimental systems using sodium acetate trihydrate. The thermal characteristics of two different water tanks were analyzed at 2, 6 and 10 L/min when the inlet temperature was 20 °C and the initial high temperature was 80 °C. The test results indicate that adding PCMs helps to provide an extra 1.4% of stored heat, prolong the hot water outlet time, and has a better thermal stratification, compared with ordinary water tanks. However, PCMs do not give off heat quickly at high flow rates. Besides the exergy efficiency (EE) gradually decreasing, the MIX number first decreases and then increases; the fill efficiency (FE) has the opposite trend with the flow increasing. FE has a max of 0.905 at 6 L/min.

• A water storage tank designed for geothermal heating incorporates a flow equalizing plate within the tank, significantly improving temperature stratification and the heat storage/release performance of the tank. • An exclusive experimental platform was built to evaluate the water storage tank's performance, facilitating simultaneous exploration of various functionalities. • The research results indicate that the new type of water storage tank significantly enhances temperature stratification and heat storage/release performance compared to traditional water storage tanks. This is of crucial significance for improving the utilization efficiency of geothermal resources and reducing the costs associated with geothermal heating. To enhance the utilization of geothermal energy in a geothermal heating and energy storage coupling system, a new water storage tank is proposed. The tank's structure comprises a horizontally designed multi-slot form with a flow equalizing plate positioned in the middle. Subsequently, an experimental system for evaluating the water storage tank's performance was designed, and a test rig was established. The study aimed to explore the thermocline's thickness variation using three distinct flow equalizing plate structures–uniform shunt, middle shunt, and side shunt—and examine the heat storage/release performance under different operational conditions. Concurrently, the applicability of the water storage tank's structure under various heat storage conditions was assessed. The findings revealed the following: (1) Under identical working conditions, the new tank displayed a thermocline's thickness proportion to the tank's height, ranging from 20.25% to 33.75%, lower than that of a traditional water storage tank. This indicates a superior temperature stratification performance for the new water storage tank. (2) At an inlet cross-sectional velocity of <0.40 m/s, the side shunt flow equalizing plate resulted in the thinnest thermocline's thickness. Conversely, with an inlet cross-sectional velocity of ≥0.40 m/s, the uniform shunt flow equalizing plate optimized the temperature stratification performance. (3) Higher initial temperatures in the tank led to reduced total heat storage and release, along with a decline in the heat release/storage ratio. For initial temperatures of 30°C, 35°C, and 40°C, the water storage tank exhibited heat release/storage ratios of 95.11%, 93.07%, and 92.04%, respectively, surpassing those of a traditional water storage tank. [ABSTRACT FROM AUTHOR]

In water distribution systems, premature decay of disinfectants inside water storage tanks can increase the costs of disinfectant input, depending on the mixing type that takes place in the tank. In this paper, the influence of the flow regime of a water storage tank upon the disinfection cost was assessed. Equations relating disinfectant cost to the disinfectant's decay rate and the mean residence time are presented and compared for three flow regimes: ideal mixed flow, ideal plug flow, and disperse flow. As the decay rate or the mean residence time increased, the cost went to the order of 100 times for plug flow, when compared to mixed flow. The dispersive flow regime presented disinfection costs that were up to 10 times the cost for the mixed flow regime. Given these differences, some general guidelines concerning baffling, inlet characteristics, and water depth-to-diameter ratio were presented in order to obtain a flow closer to the plug regime and, consequently, diminish the chlorination costs. Finally, a case study was presented, based upon the guidelines, showing that a change in the inlet diameter or inlet orientation of a water storage tank can reduce the chlorination cost. [ABSTRACT FROM AUTHOR]

Water circulation in storage tanks significantly impacts water quality in distribution networks since old water tends to have low residual chlorine concentrations that are insufficient to neutralize microbial regeneration. Their large capacity and long residence times result in uneven mixing, which can accelerate the disinfectant decay and the formation of potentially carcinogenic disinfection by-products. The phenomenon is strongly related to the tank inflow conditions, since there are no active mixing devices. This paper presents a comprehensive analysis of the flow dynamics in circular storage tanks using a three-dimensional computational fluid dynamics model. The main motivation is that the inflow—which mixing processes rely on—strongly influences the circulations. The numerical analysis provided includes a thorough investigation of interest in understanding flow dynamics for two inflow configurations: (i) the plunging jet modelling and comparison with published experimental data and (ii) the submerged jet as an improvement measurement for these storage tanks.

Controlling residential thermal loads and thermal energy storage is a viable tactic to engage end-users in demand response programs (DRPs). This paper focuses on the development of an optimal real-time thermal energy management system (TEMS) for smart homes to respond to DRP for peak-load shifting. The proposed TEMS combines two model predictive controllers to manage two thermal energy storage systems, a water storage tank (WST) and the building thermal mass, to schedule residential heat pump loads to off-peak periods. The intention is to manage the operation of a ground source heat pump (GSHP) to produce the desired amount of thermal energy by controlling the volume and temperature of the stored water in the WST while optimizing the operation of the heat distributors to control indoor temperature. The primary contributions are the development of a new control strategy for GSHPs coupled with WST based on building identification to minimize total energy consumption and cost. This paper also proposes a real-time indoor dynamic temperature set-point strategy based on real-time pricing tariffs for enhancing peak-load shifting of heat pump loads with an acceptable variation in thermal comfort. Simulation and experimental results demonstrate that the proposed TEMS has significant potential for real-time peak-load shifting. [ABSTRACT FROM AUTHOR]

Abstract Operation of a water storage tank in a specific environment motivates mathematical studies on a discrete-time deterministic dynamic programming problem. The operator decides whether or not to open the valve releasing the water in the tank to a drip irrigation system, based on the information on the storage volume of the tank. Two cases of functional regularity, which are Lipschitz continuous and of bounded variations, are considered for the reward defining the performance index to be maximized. Firstly, it is shown that the value function inherits the Lipschitz continuity of the reward in the infinite time horizon problem with discounting. Then, time periodic value functions are discussed in terms of the fixed-point theorem. Discrete approximation of value functions is discussed as well, to conduct numerical experiments with a-posteriori error estimation applied to the real-world problem where the discount rate approaches to unity. It is found that a Skiba point appears as a threshold of valve opening for each day in an optimal policy for operation. Practically, setting a constant threshold throughout the period is quite reasonable and acceptable for the operator of the water storage tank to irrigate the farmland. [ABSTRACT FROM AUTHOR]

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Water storage tanks in cities are usually large and are occasionally affected by earthquakes. A sudden earthquake can cause pressure pulses that damage water containers severely. In this study, the sloshing motion in a high filling level tank caused by seismic excitation is investigated by the numerical method in a 2D model. Two well-studied strong earthquakes are used to analyze the broadband frequency nonlinear displacement of the tank both in the longitudinal and vertical directions. Based on careful experimental verification, the free surface motion and the elevations at the side wall are captured, and the sloshing pressure response is examined. The results show that the 2D section of the cylindrical tank can be used to estimate the maximum response of the 3D sloshing, and the water motions under the seismic excitations are consistent with the modal characteristics of the sloshing. The time histories response of the water motion reflected that the sloshing response is hysteretic compared with the seismic excitation. The anti-seismic ability of the damping baffle shows that its effect on sloshing pressure suppression is limited, and further study on the seismic design of water tanks in earthquake-prone regions is needed.

The flavivirus epidemiology has reached an alarming rate which haunts the world population including Malaysia. World Health Organization has proposed and practised various methods of vector control through environmental management, chemical and biological orientations. However, from the listed control vectors, the most crucial part to be heeded are non-accessible places like water storage and artificial container. The objective of the study was to acquire and compare various accuracies and cross-entropy errors of the training sets within different learning rates in water storage tank environment which was essential for detection. This experiment performed transfer learning where Inception-V3 was implemented. About 534 images were trained to classify between Aedes Aegypti larvae and float valve within 3 different learning rates. For training accuracy and validation accuracy, learning rates were 0.1; 99.98%, 99.90% and 0.01; 99.91%, 99.77% and 0.001; 99.10%, 99.93%. Cross-entropy errors for training and validation for 0.1 were 0.0021, 0.0184 whereas for 0.01 were 0.0091, 0.0121 and 0.001; 0.0513, 0.0330. Various accuracies and cross-entropy errors of the training sets within the different learning rates were successfully acquired and compared. [ABSTRACT FROM AUTHOR]

Due to the latent heat performance of the phase change materials during the phase change process, if they are used in a solar energy storage tank, the heat storage efficiency and the heat release capacity of the tank can be effectively improved. In this study, a water storage tank containing two types of phase change materials with different melting points was proposed. Then, based on simulation calculation, the tank with the highest performance of thermal storage was obtained by changing the thickness of the phase change materials. Finally, three water storage tanks with different contents of phase change materials, respectively equipped with a circulating water system were established; the time of storing and releasing heat as well as the total amount of heat release were measured at releasing heat temperature of 40 and 45 °C. Results show that the presence of the phase change materials with different melting points can significantly shorten the time of storing heat. An increase in the contents of phase change materials in the tank leads to evident growth of heat release. At 40 °C, the amount of heat release are 21.35, 27.01 and 29.78 MJ at the contents of 0, 11.12% and 19.17% respectively, which are larger than those at 45 °C. The storage tank can reduce the use of electric heating devices and can be used in solar hot water systems. [ABSTRACT FROM AUTHOR]

AP1000 is a standard design developed by Westinghouse for an advanced generation III+ nuclear power plant (NPP) utilizing passive features. Water storage tank of AP1000 plays an important role in cooling down the temperature of the inside of the NPP. However, the water sloshing and fluid-structure interaction effects of AP1000 water storage tank have an important influence on the dynamic response and safety of the nuclear power plant under strong ground motions. In this study, a fluid-structure interaction algorithm of finite element technique is employed to investigate the seismic response of water tank with internal baffles. Four schemes of ring baffle types are considered and the effects of various parameters, such as vertical baffle height, arrangements, and length of baffle on the dynamical response of shield building are investigated. It is indicated that the case 1 with vertical ring baffle near the bottom of tank is the best scheme for reducing dynamic response of shield building in AP1000. [ABSTRACT FROM AUTHOR]

AP1000 is a standard design developed by Westinghouse for an advanced generation III+ nuclear power plant (NPP) utilizing passive features. Water storage tank of AP1000 plays an important role in cooling down the temperature of the inside of the NPP. However, the water sloshing and fluid-structure interaction effects of AP1000 water storage tank have an important influence on the dynamic response and safety of the nuclear power plant under strong ground motions. In this study, a fluid-structure interaction algorithm of finite element technique is employed to investigate the seismic response of water tank with internal baffles. Four schemes of ring baffle types are considered and the effects of various parameters, such as vertical baffle height, arrangements, and length of baffle on the dynamical response of shield building are investigated. It is indicated that the case 1 with vertical ring baffle near the bottom of tank is the best scheme for reducing dynamic response of shield building in AP1000. [ABSTRACT FROM AUTHOR]

Aedes aegypti mosquitoes are a small slender fly insect that spreads the arbovirus from flavivirus vector through its sucking blood. An early detection of this species is very important because once these species turn into adult mosquitoes a population control becomes more complicated. Things become worse when difficult access places like water storage tank becomes one of the breeding favorite places for Aedes aegypti mosquitoes. Therefore, there is a need to help the field operator during the routine inspection for an automated identification and detection of Aedes aegypti larvae, especially at difficult access places. This paper reviews different methodologies that have been used by various researchers in identifying and counting Aedes aegypti. The objective of the review was to analyze the techniques and methods in identifying and counting the Aedes Aegypti larvae of various fields of study from 2008 and above by taking account their performance and accuracy. From the review, thresholding method was the most widely used with high accuracy in image segmentation followed by hidden Markov model, histogram correction and morphology operation region growing. [ABSTRACT FROM AUTHOR]

This paper reports the overall thermal performance of a cylindrical parabolic concentrating solar water heater (CPCSWH) with inserting nail type twisted tape (NTT) in the copper absorber tube for the nail twist pitch ratios, 4.787, 6.914 and 9.042, respectively. The experiments are conducted for a constant volumetric water flow rate and during the time period 9:00 a.m. to 15:00 p.m. The useful heat gain, hourly solar energy collected and hourly solar energy stored in this solar water heater were found to be higher for the nail twist pitch ratio 4.787. The above said parameters were found to be at a peak at noon and observed to follow the path of variation of solar intensity. At the start of the experiment, the value of charging efficiency was observed to be maximum, whereas the maximum values of instantaneous efficiency and overall thermal efficiency were observed at noon. The key finding is that the nail twist pitch ratio enhances the overall thermal performance of the CPCSWH.