Cold Water Tank Research Articles

Effects of a device containing heat pipe sticks on thermal performance of a heat exchanging tube: An experimental study

Applying heat pipes (HP) on heat-exchanging tubes is the main idea of this experimental work. One, two, or three mini copper heat pipes are soldered around a cooper ring to form a new device to passively enhance the performance of a heat-exchanging test tube. The test tube, containing a hot turbulent flow of water-EG solution, is inserted into a cold-water tank. The hot-flow regime is turbulent with Reynolds numbers of 5600 to 10,700. The results for fully developed turbulent flow were compared with existing correlations to validate the experimental setup. The validation showed less than a 10 % difference in both Nusselt number and friction factor. The base fluid in the heat pipes are distilled water and dilute Cu-water nanofluids. The nanofluids with different concentrations (50, 100, 150, and 200 ppm) are applied in HP-sticks. The role of the Cu-nanoparticle's concentration on the performance of the presented device is discussed. The results reveal the notable performance of the device in the target goal. It is reported that the presented device containing HP-sticks filled with water enhances convection rate of the test tube up to 35 %. It is also ascertained that applying the Cu-water nanofluid in the HP-sticks lead to about 14 % better thermal performance, compared to water. The outcomes also reveal that dilute Cu-water nanofluids (φ≤100 ppm) notably improve the device's performance. Conversely, more concentrated nanofluids possibly decrease the device's performance.

Dual harvesting from exhaust gas of diesel generators using thermoelectric generators and cold water tank

The present work concerns a dual harvesting concept applied to exhaust gas of Diesel generators using thermoelectric generators and cold water tank. To proceed, a simplified thermal modelling is developed and appropriate parametric analysis of power generation with the TEGs and heat recovered is conducted in function of the Diesel generator power and the TEG thermal conductivity and thickness. It was shown that powers up to 534 W can be generated with the TEGs and heat recovery rates up to 4463 W can be obtained for a Diesel generator power of 125 kW. Also, it was shown that the temperature difference across the TEGs and the power generated increase exponentially when the Diesel generator power and ratio of thickness to thermal conductivity of TEGs increase.

A Study on The Presence of Legionella pneumophila in Hospital Water Samples from Eastern Turkey

Objective: Legionnaires' disease is a fatal form of pneumonia brought on by an infection mostly caused by the 60 different species of Legionella pneumophila. Legionnaires' illness is caused by Legionella spp.-contaminated water systems. In this work, we sought to analyze Legionella species, serogroups (SG), and contamination in the water sources of hospitals in five regions in eastern Turkey.
 Methods: Between January 2017 and December 2018, a total of 1008 samples were examined, including 2 cooling towers, 62 hot water tanks, 104 cold water tanks, and 840 faucet shower heads. Samples were collected by the standard culture method L. pneumophila SG 1, it was analyzed for L. pneumophila SG 2-16 and Legionella spp. The samples were inoculated into BCYE and GVPC medium, and the colonies were assessed using a latex agglutination test, followed by species- and serotype-level identifications.
 Results: In our study, a total of 1008 water samples were examined, of which 35.31% (356) belonged to 2017, while 64.68% (652) belonged to 2018. 83.33% of the water samples were taken from faucets and shower heads, 10.32% from the cold water tank, 6.15% from the hot water tank, and 0.2% from the cooling tower, and the highest positivity rate was observed in the hot water tank with 12.60%. 7.04% (71) of the samples were positive, and 16.9% (12) of the positive samples were L. pneumophila SG 1, 77.46% (55) L. pneumophila SG 2-14 was detected, while 5.63% (4) were nonpneumophila (Legionella spp) it has been determined as.
 Conclusions: Legionella disease remains a significant public health threat. The water tanks of hospitals and hotels should be investigated more thoroughly, the necessary disinfection procedures should be carried out frequently. All hospitals should have water management policies, and towns and large buildings should establish comprehensive water system management programs that decrease Legionella growth and transmission. To enhance prevention measures and clinical diagnosis, we also need quicker ways of detecting Legionella in water systems and clinical samples.

Development of a Constant Temperature Hot and Cold-Water Supply System (CT50WS) for Laboratory Application

Over 95% of Nigeria undergraduate students enrolled in public universities. Public universities in Nigeria are however poorly funded and lack adequate facilities. The recent rise in the foreign currency against the Nigerian Naira has further increase the cost of purchasing and maintaining foreign equipment. In this work, a constant temperature hot and cold-water supply system (CT50WS) for laboratory application was developed. This is to explore the production of equipment locally. The developed system was tested on a load and no-load conditions. A shell and tube heat exchanger were used to simulate the load on the component. The system was designed to heat and cool 50 liters of water independently. Results of the tests carried out on the constructed CT50WS on no load condition showed that the actual rate of heat loss from the hot water system is 34.4W. The actual rate of heat gain from the cold-water tank is 16.03W, far lower than the designed heat gain rate of 74.9 W (10%) heat gain rate. When tested on-load condition, the CT50WS was able to continuously supply 100 litre/hr of hot and cold water at a temperature of 50 and 18oC respectively to the heat exchanger. The open market cost of a similar foreign equipment is about 25 times the cost of CT50WS. Its acceptability will further open opportunities in local production of teaching and research equipment, thereby serving as source of job creation and saving the scarce foreign currencies.

Predictive investigation of the combined heat storage system using at NPPs with VVER

The increase in the share of nuclear power plants in the energy systems leads to the need for their participation in covering the irregularities in the electrical load schedules. NPPs unloading is economically unsustainable. Combining NPPs with storage systems can be a solution to this problem, as it will allow the reactors to operate at a constant capacity utilization factor, while excess energy will be stored during load dip hours and converted into electrical energy during peak load hours. The authors have developed a thermal storage system based on the combination of a phase change accumulator with hot and cold water tanks. The system also contains a steam turbine to generate electricity during peak hours using stored energy. Earlier the authors proved that a low-power turbine can be used to supply power to the NPP auxiliary needs with a blackout using only residual heat energy. In this paper, a methodology for determining the necessary operating parameters of the storage system for using under the required conditions is presented. The investigation of economic efficiency was carried out on the example of a range of electricity tariffs for the world’s energy systems. Accumulated net present value ranged from $0 to $85 million.

Performance analysis of a solar-assisted dual-tank heat pump system for climatic conditions in Turkey

This study aimed to analyze the performance of a solar-assisted dual-tank heat pump system under climatic conditions in Turkey. This system and its components were modeled and simulated using transient system simulation software. The system was designed not only to supply domestic hot water for a restaurant, but also to heat it in winter and cool it in summer. The modeled system works on the principle that a water-to-water heat pump operating between dual tanks transfers the heat from the cold water tank (source side) to the hot water tank (load side). The hot water for both heating and domestic hot water is supplied from the hot water tank throughout all seasons, whereas, the cold water is supplied from the cold water tank for cooling the space in summer. A photovoltaic thermal collector was integrated into the cold water tank to support the source side of the heat pump and also to generate electricity for the system in winter, but was used only for producing electricity in summer. Analyses were carried out for five provinces (Istanbul, Ankara, Izmir, Hakkari, and Trabzon) located in five different regions of Turkey. According to the simulation results, the highest seasonal performance factor (2.65) was obtained for Izmir, whereas the lowest seasonal performance factor value (1.74) was obtained for Hakkari. The system worked 52% more efficiently in Izmir than in Hakkari. With the photovoltaic thermal collector, 17.68% of the total electrical energy consumption of the system was compensated for Izmir Province and 12.09% for Hakkari Province.

Efficiency investigation of the combined heat storage system using at NPPs with VVER

Using of consumer-regulators at NPPs will make it possible to increase the share of nuclear power plants in the power system due to the expansion of their use range with a constant installed capacity utilization factor of reactors. As a result, the renewal of the maneuverable capacities of the power system can be carried out with the reduction of power plants, operating on fossil fuel, which will lead to a decrease in emissions causing irreparable harm to the environment. In the article, the heat storage system developed by the authors is presented and researched. It includes a phase change accumulator, cold and hot water tanks and additional steam turbines, which will avoid expensive main turbine modernization and its deterioration magnification, also it will provide an additional reserve for the NPP’s own needs. The results of investigation conducted for a wide range of operating conditions have shown that systems pay off completely under certain conditions. The authors also showed that the installation of a hot water tank can reduce capital investment in a heat storage system based on a phase change accumulator.

KAJI KARAKTERISTIK PERPINDAHAN PANAS PENGARUH BELOKAN TAJAM PADA PENUKAR KALOR TIPE TUBE

Using the thermal machines in the production process or overdone heat power operation require unit of Heat Exchanger (HE) having high level heat transfer coefficient (hc) for transferring to the thermal reservoir. Experimental studies have been done for heat transfer characteristics of forced convection on the round duct with method use that compare three of heat exchanger with a variety of pipe bends and a long pass after a turn that is different. HE pipes have length of tube 500 mm with a 12 bends, HE pipes length of tube 250 mm with 24 bends and HE pipes length of tube 125 mm with 48 bends. The heat fluid flowed into the tube, and the tube is immersed in the cold water tank. For each of test equipments can be done three times experiment with different variations in inlet temperature that is at 600C, 700C and 800C, with a duration of 5 minute intervals for 50 minutes. Many pipe bends and short passes after a HE will increase turbulence flow pattern. The high of turbulence will increase the value of heat transfer coefficient, but it can hold on fluid flow rate. Keywords : heat transfer characteristics, round duct, sharp bends, long pass

Thermoelectric Water Cooler and Heater with Intermediate Water Tank

This paper presents a mathematical model to investigate the effect of intermediate water tank for cascade configuration of thermoelectric modules in heating and cooling application. The system consists of two thermoelectric modules separated by an intermediate water tank. Another surface of each thermoelectric module is in contact with cold water tank or hot water tank. In the simulation, both hot and cold water tanks consist one kilogram of water. The mass of water in the intermediate water tank was set to 0.01 kg (negligible thermal mass), 1 kg (equal thermal mass) and 10 kg (large thermal mass). Set point for hot and cold water tanks was 373 K and 276 K, respectively. It was found that intermediate water tank with higher thermal mass enable a better temperature control and produces higher Coefficient of Performance for both thermoelectric modules. These findings are essential for the development of a three-stage temperature water dispenser using thermoelectric modules.

Optimization and performance of a small scale adsorption cooling system fully powered by solar energy for hot arid areas

The aim of this study is to identify the optimal design parameters of a fully solar-powered adsorption cooling system for residential buildings located in hot arid areas. The proposed system consists of solar collectors, hot water tank, water–silica gel adsorption chiller of 8 kW cooling capacity, cold water tank, fan coil unit, and cooling tower. An optimization based on computer simulation has been conducted for achieving the aim of this study. The proposed system was applied to Assiut, Egypt as a case study. The optimization shows that the optimal design parameters of the proposed system are as follows: 58 m2 solar collecting area, 5.5 m3 hot water tank and 1 m3 cold water tank. The simulation of the proposed system with the optimal design parameters during the design day shows that the chilled water temperature leaving the chiller is between 17 and 18 °C with high cooling water temperature of 34.5 °C. This makes the system unable to achieve the indoor thermal design conditions. However, the system is able to meet the cooling demand in most days of the cooling season except for about 9.15% representing extreme hot days. The simulation also shows that during the design day, the proposed system achieves daily solar collecting efficiency of 56% and can produce chilling energy of 113.3 kWh with 7.35 kW energy rate and daily COP of 0.41. In addition, the cold water tank enables the system to extend the operation period for 110 min after switching off the chiller.

Parametric Analysis of Solar Heating and Cooling Systems for Residential Applications

In this paper, a parametric analysis of two solar heating and cooling systems, one using an absorption heat pump and the other one using an adsorption heat pump, was performed. The systems under investigation were designed to satisfy the energy requirements of a residential building for space heating/cooling purposes and domestic hot water production. The system with the absorption heat pump was analyzed upon varying (i) the solar collectors’ area, (ii) the volume of the hot water storage, (iii) the volume of the cold water tank, and (iv) the climatic conditions. The system with the adsorption heat pump was evaluated upon varying (i) the inlet temperature of hot water supplied to the adsorption heat pump, (ii) the volume of the hot water storage, (iii) the volume of the cold water tank, and (iv) the climatic conditions. The analyses were performed using the dynamic simulation software TRNSYS in terms of primary energy consumption, global carbon dioxide equivalent emissions, and operating costs. The performance of the solar heating and cooling systems was compared with those associated with a conventional system from energy, environmental and economic points of views in order to evaluate the potential benefits.

Design and experimental investigation of a novel thermoelectric water dispenser unit

In this study, a novel thermoelectric water dispenser unit is proposed to supply cold and hot drinking water simultaneously. For this purpose, the heat sinks attached to the cold and hot surfaces of a Peltier module are placed into the cold and hot water tanks of the thermoelectric water dispenser. Supplying power to the thermoelectric module, the cold water tank is cooled while the hot water tank is heated at the same time. The cooling and heating performances of the system are examined for three cases: the tanks made of glass walls without insulation; the tanks made of polyethylene walls without insulation: and the tanks made of polyethylene walls with insulation. Results show that water tanks with polyethylene walls have better thermal performance than those with glass walls. Furthermore, insulation of the tanks has a significant enhancement in COP especially on the heating side. Results of this study also indicate that TE water dispenser can compete with conventional types, with the advantages of being environment-friendly, smaller, silent and operable with renewable energy sources.

Modeling and optimal operation of community integrated energy systems: A case study from China

The operation of community integrated energy systems (CIESs) is challenging because it is necessary to couple energy production, conversion and consumption on the end-user side. Multiple energy demands need to be fed simultaneously with the goal of economy and reliability. This paper formulates the optimal scheduling problem based on a real community integrated energy system in China. The system has multiple chillers (i.e. three ground source heat pumps, two conventional water-cooled chillers and two double-duty chillers) and two types of thermal storage devices (i.e. two cold water tanks and an ice-storage tank). Based on detailed device modeling, a community integrated energy system operation strategy considering unit commitment is proposed, and then is transformed into a mixed-integer linear programming model by linearization of nonlinear items. Case studies are conducted based on the data for a typical day in summer. The results show that the proposed strategy can utilize the flexibility of the energy storage devices and realize an economic and reliable operation of the community integrated energy system by coordinating various energy devices. The strategy can also reduce the startup/shutdown frequency of chillers significantly.

Experimental comparison of longitudinal and annular fins using PCM for Thermal energy storage

This work deals with comparative study of longitudinal and annular fin using PCM in a thermal energy storage unit experimentally and numerically. The TSU under analysis Consists of paraffin wax as PCM with melting Temperature of 55°C to 60°C. Liquid heat transfer fluid passes between the tubes to charge and discharge the storage unit. Thermal storage tank is connected to the experimental setup which consists of hot and cold-water tanks and experiment is carried our initially charging and discharging by Longitudinal fin process by passing heat transfer fluid similarly the charging and discharging by Annular Fin process by passing heat transfer. The experimental results show that usage of Longitudinal fin and Annular fin for charging and discharging has different heat transfer rate. Even efficiency is increased around 6% for the longitudinal finned heat exchanger than the Annular finned heat exchanger.

Experiments and numerical simulation for a thermal vertical jet into a rectangular water tank

Abstract In this paper, experimental measurements and numerical CFD calculations are carried out for the problem of a vertical thermal water jet into a rectangular water tank. We consider two cases; the first case is to inject a hot-water jet with a uniform inlet temperature (UIT) into a cold-water tank. The second case is to inject a cold-water jet with non-uniform inlet temperature (NUIT) into a hot-water tank. In the UIT case, we examine the effects of the temperature-difference. In the case of NUIT, we studied the effects initial temperatures with constant flow rate; and different flow rates at constant initial temperature. Both turbulence intensity and Reynolds number are formulated to be a function of the inlet temperature for the NUIT case. The numerical simulations are carried out under the same conditions of the experiments. We use the realizable k - e model to describe the turbulent flow with the energy equation. The symmetrical 3D half of the tank has been considered to reduce the computational cost. The water density is treated as a piecewise-linear of temperature. The turbulence at the inlet is characterized by the hydraulic diameter and the turbulence intensity. Several quantities are obtained and analyzed such as pressure, velocity, temperature, and turbulence. A good agreement between simulation and experimental results at low temperatures, while at high temperatures there is acceptable agreement with some quantitative differences. In spite of there are some differences between the measurements and the simulation in a certain case, nevertheless, the qualitative comparison is quite well. The thermal stratification occurs clearly with high temperature-difference, however, after a certain time, the thermal stratification is mixing. Moreover, when a cold-water jet enters a mixed hot water tank, stratification comes early and after a certain time, it mixes. For the UIT cases, the tank is totally mixing, while, for the NUIT cases the stratification clearly occurs.

Thermal Conductivity Measurement of A Bar-like Object

A new experimental setup for measuring the effective thermal conductivity of a bar-like object was proposed in the paper, and the analysis for the data reduction was also given theoretically. The designed setup consists of two identical water tanks connecting respectively with the two ends of the measured bar-like object. Two similar mixing stirrers are installed inside the cold and hot water tanks, respectively, in order to realize the same convective boundary conditions at the two ends of the cylindrical object. Therefore, an approximately one-dimensional transient heat conduction will occur after one of two water tanks filling up with hot water and the rest facilities are at room temperature initially. By continuously reading the water temperatures inside the two tanks, and/or the end surface temperatures of the cylindrical object if permeable, its effective thermal conductivity can be measured. It is believed that the proposed methods have several merits over some conventional methods: (1) no need for the cutting measurement sample from the main object; (2) easy implementation; (3) data analysis can be much simplified by using identical water tanks and mixing stirrers; (4) the system is much reliable since the process of the method uses multi-position temperature data matching, include the hot tank, the cold tank, the hot end. In addition, this method is especially suitable to measure a bar-like object with a larger thermal conductivity. Finally, an error analysis for the proposed method was given.

Performance of off-grid photovoltaic cooling system with two-stage energy storage combining battery and cold water tank

This paper proposes an off-grid PV cooling system with TSES combing BS and CWST and investigates the influence of battery efficiency, tank insulation and chiller schedule on system efficiency and storage capacity. TRNSYS is employed to study the specific performance of this system. The results indicate that, in comparison with SBS and SCWST, the proposed TSES can rise system efficiency by 6.73% and 10.27% under convex cooling load while by 7.16% and 10.50% under ascending one.

Experimental Study on a Line-Axis Concentrating Solar Energy Collector for Water Heating

This paper examines the experimental study on a line axis concentrating solar energy collector for water heating. The system considered consists of cylindrical solar radiation concentrator with a black coated tubular absorber positioned along its axis. A cold water tank is placed above the collector and a hot water tank positioned below it such that fluid flows in and out of the set up. Solar radiation absorber inlet header is connected to the cold water tank while its outlet header is connected to the hot water tank. These major components are supported by angle iron raised at a distance from the ground that depends on the location and function. Valves are used at strategic points on the connecting pipe lines to isolate the flow of water. When water is poured into the cold water chamber, and the control valve turned on, the water flows under gravity into the receiver/absorber tube. At the absorber section, heat is transferred from the steel tube to the circulating water and is consequently heated. The heated water, then flows into the returning tube against gravity, thereby restricting the heated water from flowing into the storage tank. At this stage, thermo-siphoning effect comes into play. As the temperature of the water increases, its density reduces while the mass remains constant in order to balance the effect of the reduction in density. Thus, there is a resultant increase in volume which consequently pushes the water level further along the returning pipe. Further increase in temperature reduces the water density and increases the volume of the water, thereby causing the heated water to flow into the insulated tank. Several experimental tests were carried out under meteorological condition at the Federal University of Technology Owerri, Nigeria at three different mass flow rates of 0.001kg/s, 0.002kg/s and 0.003kg/s. The solar water heater was tested while oriented in the East–West and North –South directions in order to determine the effects of orientation on the performance. Results obtained showed that a maximum temperature of 69.5°C, corresponding to 34.5°C increase in water temperature and a maximum instantaneous efficiency of 51.01% is possible. The aim of the study is to design a cheaper solar energy system capable of reducing energy bill within the developing countries of the world.

Thermo-economic analysis of the energy storage role in a real polygenerative district

This paper presents a thermo-economic analysis based on data from a real Smart polygeneration microgrid (SPM), designed to satisfy energy demands of the university campus of Savona (Italy). The plant is made up of different cogenerative generators (micro gas turbines and an internal combustion engine), renewable generators and two auxiliary boilers (one of them is off during the most of the time): the generators are “distributed” around the campus and coupled to electrical and thermal storages. Since several cogenerative units are included in the grid, the integration of the different storage systems is relevant in order to determine the best management strategy, following both thermal and electrical requests and taking into proper account the strong difference between the two energy demand profiles.The thermo-economic analysis is performed exploiting the software W-ECoMP, developed by the authors’ research group, in order to find the best operational strategy, considering the importance of an appropriate storage system to manage the polygenerative energy district; attention is paid to the integration and combination of three different kinds of storage (hot and cold water tanks and electrical battery). Different scenarios are presented, combining the storages and showing their impact in terms of money savings and reduction of electrical energy purchasing from the National grid. Both the grid connected mode and island mode of operation of the SPM are considered.The analysis is performed considering the time dependent nature of the energy demands throughout the whole year and implementing the experimental off-design curves of the real devices installed in the grid.

Design, Construction and Evaluation of Zobo Juice Processing Device

This study was aimed to develop a device which can process Zobo juice at an economic rate utilizing the principle of leaf extraction method. Four tanks were constructed using aluminium sheet and stainless steel. The boiling, heat exchanger, and homogenizing tanks were made of aluminium while the cold water tank was made of stainless steel. The volumes of the tanks are 9.0 m 3 , 9.5 m 3 , 9.0 m 3 and 5.0 m 3 for boiling tank, homogenizing tank, heat exchanger and cold water tank respectively. The Zobo calyces are boiled in the boiling tank and the product is exited into the heat exchanger where water from the cold water tank is allowed into the heat exchanger to reduce the temperature of the zobo juice after which it finally enters the homogenizing tank where other ingredients (sugar and ginger) are added. The homogenizing tank stirs its content to obtain the final product. Its performance showed that in an average of 32 minutes using 9 litres capacity of boiling tank with mean volume of 9.0 cm 3 , the homogenizing tank with mean volume of 9.5cm 3