Water Temperature In Tank Research Articles

Geometry change impact on thermal efficiency with large volumetric sensible heat storage tank

AbstractBy installation in district heating and cooling systems, large volumetric sensible heat storage tank is a technology that can reduce CO2 emissions into the atmosphere, ensure the integration of renewable energy sources into district heating and cooling systems, overcome the mismatch between production and demand and increase reliability and efficiency of entire systems. Such tanks operate on the principle of temperature stratification. In this paper, the processes of charging and discharging the heat storage tank used in district heating systems depending on the geometric and process parameters are analyzed and the thermal efficiency of each of these processes is calculated. The thermal efficiency of the tank charging process is calculated based on the distribution of the warmer water temperature in the tank after the complete tank charging process and varies between 53.85% and 96.75%. The thermal efficiency of the tank discharging process was calculated based on the warmer water outlet temperature and varies between 87.83% and 96.00%. Validation of mathematical model was achieved by comparing the data obtained by measuring the water temperature in the heat storage tank installed in the city thermal power plant‐heat plant and the results of numerical calculation.

Simulation analysis and experimental validation of enhanced photovoltaic thermal module by harnessing heat

A novel thermally regenerative electrochemical cycle (TREC) has been developed recently for converting low-grade heat into electricity, which is suitable but rarely researched for harnessing the thermal energy generated by the photovoltaic/thermal (PV/T) module to enhance the electrical performance. This study conducts experimental works on the heat-to-electricity performance of the TREC battery to demonstrate the feasibility and superiority of the PV/T-TREC hybrid system. Based on the experimental results, a detailed transient three-dimensional MATLAB simulation model of the PV/T-TREC system is developed to predict the overall electrical performance. For practical applications, the annual behaviors of the PV/T-TREC system employed in three typical climate areas of Hefei, Beijing, Harbin are simulated and compared. The results show that the electrical performance of the hybrid system is better than the single PV and PV/T module during different areas of various weather conditions except for cold season of February and November in Harbin. In comparison to the PV/T, the hybrid system can generate additional electricity of 45.95 kWh/m2, 50.20 kWh/m2, 29.99 kWh/m2 in the locations of Hefei, Beijing, Harbin annually. To reach the maximum electrical efficiency at different amounts of solar radiation, optimal tank volumes are analyzed and suggested in different months. The optimal working temperatures for the maximum electricity output on ideal theoretical analyses are 72 ℃, 83 ℃, 91 ℃, 100 ℃ at the ambient temperature of 5 ℃, 15 ℃, 25 ℃, 35 ℃ in constant heat cases. This study may provide a feasible plan for designing the water tank and water temperature of the PV/T-TREC for achieving high-efficient annual electricity performance of solar power in different application locations.

Performance on Power, Hot and Cold Water Generation of a Hybrid Photovoltaic Thermal Module

This paper proposed a new function of photovoltaic thermal (PVT) module to produce nocturnal cool water not just only generating electrical power and hot water during daytime. Experimental tests were carried out under Chiang Mai tropical climate with a 200 Wp monocrystalline PVT module having dimensions of 1.601 m × 0.828 m connected with two water tanks each of 60 L taken for hot and cool water storages. The module was facing south with 18o inclination. The electrical load was a 200 W halogen lamp. From experiments, by taking the module as a nocturnal radiative cooling surface, the cool water temperature in the cool storage tank could be reduced 2oC–3oC each night and the temperature could be reduced from 31.5oC to 22.1oC within 4 consecutive days. The cool water at approximately 23oC was also used to cool down the PVT module from noon when the PVT module temperature was rather high, and then the module temperature immediately dropped around 5oC and approximately 10% increase of electrical power could be achieved. A set of mathematical models was also developed to predict the PVT module temperature and the hot water temperature including the cool water temperature in the storage tanks during daytime and nighttime. The simulated results agreed well with the experimental data.

An Experimental Study on the Performance of a Hybrid Photovoltaic/Thermal Solar System

Considered as the widespread renewable energy, solar energy is used to produce the electricity and heat for carbon peaking and carbon neutralization. However, the photo-electric conversion efficiency will decrease with the increase of cells temperature. To solve this problem, a water-type hybrid photovoltaic/thermal (PV/T) solar system has been designed and tested in Hong Kong. The outdoor experiment proceeded all days in 6 months with three different operating modes. The data of selected 33 days were used to analyze the performance of the system. The results showed that the thermal efficiencies were 33.6%, 52%, and 48.3% at zero reduced temperature, corresponding to three modes. Besides, the overall efficiencies were 43.2%, 60.9%, and 55.2% accordingly, which are higher than those of the conventional flat-plate solar collector. The average water temperature in the storage tank could reach 39.9°C, and the system could produce 0.07 kWh electric power after one-day operation, when the collector with 96 kg/m2 M/Ac installed vertically combining with external wall for each family. It is realizable to utilize the developed building integrated water-type photovoltaic/thermal (BIPVT) solar system for residentialintensive high-rise buildings in Hong Kong, satisfying the needs of hot water, and eventually reducing energy consumption of the buildings.

Control of ship tank heating systems to increase their energy efficiency

An important problem in the operation of icebreakers and Arctic ships is to prevent excessive icing of ballast tanks above the waterline. Uncontrolled ice formation can damage ballast systems and lead to malfunctions of ballast systems during cargo operations. This paper presents an analysis of the dynamics of water temperature in a ballast tank when the heating system is turned on and off. Recommendations on the control algorithm for the heating system that provides maximum energy efficiency are proposed.

Investigation of the effect of deposit layer on heat transfer in the Triga Mark II nuclear research reactor cooling system

In this presented study, the cooling problem of the I.T.U. Triga Mark-II reactor has been handled and analyzed, and solutions were proposed. First of all, a thermal model of the reactor, heat exchanger, and cooling tower trio was established in the reactor. With this model, which was obtained with the help of experimental data, the parameters affecting the change of reactor water temperature over time were determined, and significant findings were obtained by investigating the possibilities of increasing the cooling power of the existing system. Then, using these mathematical equations, the effects of parameters that can affect the power of the reactor cooling system are investigated. The parameters affecting the cooling power are the cooling water flow rates in the second cooling circuits and the deposited layer that may exist as a result of numerical calculations. Different models have been created with machine learning algorithms (page regression, decision tree) to estimate the effect of the deposit layer. The mathematical and predictive models obtained with the experimental data for the heat transfer coefficient of the deposit layer, hbd, were compared. The pace regression algorithm modeled the hbd values with the least error rate (RMSE: 1.66) among the models. It has been calculated that the average tank water temperature will decrease by approximately 3.5?C if the deposits layer is cleared.

Experimentally investigating the influence of static mixers on the performance of a solar water heater

For the majority of household, municipal, and corporate heated water needs, solar water heater has become an inescapable renewable source. Due to its relative benefits over alternative methods, evacuation tube collectors (ET) oriented solar water heaters (ETSWH) have become increasingly popular in recent years for the mentioned uses. Specifically, the ET system is particularly affordable and effective for the inactive operations. As a result, ETSWHs are widely used in both residential and business structures. Nonetheless, the deprived water flow at the low end of the ETs makes them idle for the majority of time and decreases the useful absorbers area, is a fundamental flaw with ET system in gravity driven type of ET operation. This work aims to address the above ET issues by producing volatility within the ET utilizing two distinct varieties of static mixers, namely combinational static mixers (CSM) and a spring type static mixers (SSM). The experimentations had been carried out in three different ways: ET without static mixers (Empty-ET), ET with combinational static mixers (CSM-ET), and ET with spring type static mixers (SSM-ET). The data was taken from all the cases and then analyzed. The inclusion of static mixers greatly increased the ET water temperature by inducing turbulence, according to the findings. They concurrently increased heat gain, resulting in an increase in mean water tank temperature. With the help of combinational static mixers and a spring type static mixers, the water in the tank's temperature was raised by 8.5 °C and 4.5 °C, correspondingly. Furthermore, as compared to spring type static mixers, the combinational static mixers appear to be superior in terms of enhancing heat transport inside the ETSWH.

Proposal and preliminary experimental investigation on a novel efficient integrated system of combined refrigeration, heating, and hot water supply

Poly-generation systems with high integration can meet various needs of users. Therefore, design and efficient operation have always been the focus of attention. In this paper, a novel multi-functional system with R410A as the working fluid is proposed. Cooling, heat, and hot water can be provided under five kinds of operation modes. The most prominent advantages of the system lie in the high integration of multiple functions and high effectiveness in the combined cooling/hot water mode. The feasibility of system integration and mode switching is firstly analyzed and validated. The variation regulations of determining variables and performance indicator, including compressor inlet and outlet pressure, valve opening, and coefficient of performance, are revealed based on the self-built experiment rig. Research results exhibit that, an increase in the water tank temperature can promote the compressor outlet pressure. The average difference of inlet pressure between water tank temperatures of 50 °C and 40 °C is 30 kPa, while that of outlet pressure is 611 kPa. The larger the charge amount, the smaller the valve opening. Besides, under typical operating conditions, the total COP of the combined refrigeration/hot water mode can reach up to 8.25, and it is 51% more efficient than that of the hot water mode.

Performance analysis on combined heat and power of photovoltaic-thermal module integrated with phase change material-water storage

Use of phase change material (PCM) to generate temperature stratification in water storage tank coupled with unglazed photovoltaic-thermal (PVT) module for combined heat and power generation enhancement was investigated by experimental and numerical analyses. In the experiment, RT42 PCM having melting point of 38–43 °C was filled in a packed-bed of 40 mm diameter spherical capsules contained in a 220 L water storage tank connecting with four units of 200 Wp (watt peak) unglazed PVT module in series. The experiments were performed outdoor with the water mass flow rates of 2.4 and 5.8 LPM. One-dimensional finite difference enthalpy method was used to predict the water and PCM ball temperatures in the tank. The PVT thermal performance was evaluated similarly to that of solar thermal collector, and the electrical performance was calculated from nominal operating cell temperature (NOCT) approach. It could be noticed that the simulated results on the water and the PCM ball temperatures including the module temperature and the maximum generated electrical power of PVT modules agreed well with the experimental data. The model was used to predict the electrical and overall (both thermal and electrical) efficiencies of the PVT modules by considering the positions of the PCM packed-bed, the PCM amount, the circulating water mass flow rate, and the PCM type. It could be found that the position of the packed-bed did not give effect on the PVT module performances but increase of the PCM amount generated higher water temperature stratification in the storage tank which resulted in higher PVT module efficiencies especially in the afternoon. The circulating water also did not give strong effect on the total PVT module performances. For PCM with low melting point, the PVT module performances were higher but the water temperature in the storage tank might be too low for hot water utilization.

Design and performance evaluation of selective energy optimization of PV/T system

PurposeThis paper aims to develop a selective energy optimisation of the photovoltaic–thermal (PV/T) system performance. The PV cell inside the PV/T system could be periodically manipulated to produce domestic hot water without applying an external power supply.Design/methodology/approachA numerical simulation model of the proposed PV/T model was developed in MATLAB/Simulink to analyse the selective energy optimisation of the model. The extrinsic cell resistance (Rse) is adjusted to control the ratio of thermal to the electrical energy, generated from the PV cell inside the PV/T system. Therefore, the internal heat of the PV cell inside the PV/T system is periodically used as a thermal element to produce electrical power and hot water.FindingsThe optimisation of PV/T energy shows that the electrical power efficiency can increase by 11.6% when Rse was 0 Ω, and the 200 L water tank temperature increased by 22ºC when Rse was 50 Ω.Originality/valueThis study showed that the use of the PV cell could be extended to domestic hot water and space heating, and not only for electricity.

Experimental Investigation on Evacuated Tube Solar Collector Using Biofluid as Heat Transfer Fluid

Bio-oil extracted from waste of different plant kernel was used as heat transfer fluid in evacuated tube solar collector. Thermal performance of the biofluids to the enhancement of the evacuated tube solar collector under varying weather conditions and experimental analysis was carried-out. Thermal analysis on the storage water tank temperature, outlet and inlet heat transfer fluid temperature, and heat gains by was studied. In addition, the biofluids thermophysical properties and degradation analysis was conducted and compared with conventional base-fluids. From the results the biofluids caused enhancement of heat gain in the collector receiver by 9.5%, 6.4% and 3.2% for moringa oleifera kernel oil (MOKO), date kernel oil (DKO) and palm kernel oil (PKO), respectively. The storage water tank temperature at night fall was 53, 49, 51 and 47oC, for the MOKO, DKO, PKO and water HTFs, respectively. The biofluids were thermal stable and with no degradation. The biofluids demonstrated potentials as heat transfer fluids in thermal applications but there are needs for more investigations on their enhancement with organically synthesized nano particles to preserve there no corrosive and toxicity nature, and experimental performance on heat exchangers after several heating cycles.

Research on Optimization of collector module of new flat plate heat pipe PV/T heat pump system

The mathematical model of a new flat plate heat pipe PV/T heat pump system is established. The experimental data of the system under various working conditions are obtained through experimental measurement, and the accuracy and reliability of the model are verified. Based on the verified mathematical model, the thermal performance, electrical performance and the performance of the heat pump system are simulated. The results show that under winter conditions, the daily average thermal power, electrical power and COP of the system are 274.5 W, 93.5 W and 2.7 W respectively. Due to the low outdoor ambient temperature in winter, during winter operation, the heat collection system will lose a lot of heat to the surrounding environment through the photovoltaic panel surface, resulting in the heat collection of the system cannot meet the heat demand of the heat pump side, which is intuitively shown as the water temperature of the heat collection tank on the evaporation side shows a downward trend throughout the day. Therefore, the collector module of the system is optimized by adding a collector. After optimization, the daily average thermal power of the system is increased to 654.2 W and the COP is increased to 6.9.

Research on combined heat and power system based on solar-proton exchange membrane fuel cell

ABSTRACT In order to solve the problem of power supply and heating in remote rural household of north China, taking rural houses in Yinchuan as the research object, a solar-proton exchange membrane fuel cell (PEMFC) combined heat and power (CHP) system that is suitable for supplying power and heating to household in remote rural areas in north China is proposed in this paper. The simulation model is developed by using the MATLAB/Simulink platform and the effects of key operating parameters (i.e. current density and active area) on the performances of the PEMFC are studied. And the control effects of PID and fuzzy PID on the outlet temperature of the PEMFC stack are analyzed. The changes in temperature of water tank and indoor heating temperature under different electric loads and solar radiation are compared and studied. Meanwhile, the change in temperature of water tank is analyzed with or without solar energy, and the electrical efficiency, thermal efficiency, and CHP efficiency of PEMFC CHP are studied. The results show that the current density and active area have a significant impact on PEMFC stack. The temperature of water tank can be increased by 20°C combining solar energy and PEMFC. In winter, under different electric loads and solar radiation, the solar-PEMFC CHP system can make the temperature of the water tank reach above 55°C, and make the indoor heating temperature reach 20°C~27°C.In addition, the maximum efficiency of PEMFC CHP system is about 83%.

Basil, Ocimum basilicum, yield in northern latitudinal aquaponic growing conditions

AbstractThe need for yield research is increasing with the popularity of aquaponic food production systems where plants and fish are grown together in a recirculating system. Our objective was to compare the yield of three basil cultivars (“Elenora,” “Genovese,” “Nufar,” Ocimum basilicum) in four configurations (greenhouses: floating raft DWS, ebb & flow, A‐frame; warehouse: floating raft; 1–8 tank replications/treatment) as well as a soilless control to establish a baseline for aquaponic producers in northern latitudes. We also tested whether basil yield varied among fish types: yellow perch, Perca flavescens, goldfish, Carassius auratus, tilapia, Oreochromis spp., and koi, Cyprinus carpio. Fish tank water temperature, nitrite, and alkalinity levels differed significantly over seasons (summer, winter). There was a significant decrease in basil production in all aquaponic systems that used koi (greenhouse, warehouse). No significant difference in basil yield was found among greenhouse and aquaponic systems for perch, tilapia, or goldfish nor among the basil “Elenora,” “Genovese,” and “Nufar.” Considerable variation occurred in yield although most of it occurred in fresh weights, being reduced significantly in dry weights. The effects of growing koi fish on reducing aquaponic production of basil is noteworthy, although future research is needed to the exact cause.

Experimental and numerical study of a PV/T direct-driven refrigeration/heating system

A photovoltaic/thermal (PV/T) direct-driven refrigeration/heating system was proposed in this paper. This system had the functions of off-grid refrigeration and hot water supply without using batteries. The solar refrigeration efficiency could also be improved by means of PV cell cooling in PV/T modules and compressor speed controlling. In this paper, performance of this system was investigated by experiments and numerical simulations. The influences of the total capacity of PV cells and water temperature in the ice storage tank were also studied. When the number of PV cells increased, the daily cooling capacity per cell increased first, then decreased. This revealed that the capacities of the compressor and PV cells should be designed to improve the PV utilization efficiency. Total cooling capacity of the system increased with the increase of initial water temperature in the ice storage tank. This revealed that high initial water temperature was benefit for system cooling capacity.

Experimental and numerical investigation on a novel photovoltaic direct-driven ice storage air-conditioning system

In this paper, a photovoltaic direct-driven ice storage air-conditioning (PDISAC) system is proposed and performance of the system is experimentally and theoretically investigated. The proposed system is a battery or inverter less photovoltaic direct-driven system where the DC compressor is directly connected to the PV array. Through the test, it has been found that the proposed system was able to lower the test room temperature below 298.15 K, while the reference room temperature was 306.15 K. Moreover, the experimental refrigeration efficiency and solar-energy utilization efficiency were reported 1.028 and 7.1% respectively. Then, a mathematical model for the progress of ice making and cold storage is presented and verified by the experimental results. Besides, the factors such as the ambient temperature, the initial water temperature and volume in the ice storage tank, and the thickness of the ice layer surrounding the coil have been studied. The simulation results indicate that the initial heat transfer rate at the condensation side drops by 10.8% and refrigeration efficiency drops by 32.7% with the ambient temperature increasing from 298.15 K to 308.15 K. The increment of initial water temperature and initial water volume will lead to an increase in refrigerating capacity and refrigeration efficiency.

Heat transfer phenomenon and characteristics study of C-shaped tube with nucleate boiling in water tank

The Passive Residual Heat Removal Heat Exchanger (PRHR HX) is an important equipment of the passive safety system in advanced nuclear power plants such as AP1000. Heat transfer phenomenon and characteristics study of the PRHR HX has received more and more attention. However, the research of transient heat transfer under C-shaped tube outside pool boiling condition is insufficient and needs further investigation. An experimental facility was built and a series of experiments were conducted. Distributing and changing tendencies of some important parameters including tank water temperature, tube wall temperature and heat transfer coefficient were obtained and analyzed. This study can provide a reference for the thermal hydraulic design for the PRHR HX in nuclear power plant.

Investigation on solar water heater with different types of turbulators

Solar water heaters have become unavoidable renewable energy systems for the most of the residential, commercial and industrial hot water requirements. Evacuated tube collector (ETC) based solar water heaters are widely used for the aforementioned purposes in recent days due to their relative advantages over other systems. Exclusively, the ETC systems are very economical and efficient for the passive operation. Hence, they are keenly installed in the commercial and residential buildings. A major hiccup with ETC systems in passive mode of operation is the poor water circulation at the lower end of the ETCs, which make them inactive in most of the time and reduces the effective absorber area. This work is planned to curtail the aforementioned issue of the ETCs by inducing turbulence using two different types of turbulators, namely coiled turbulator and matrix turbulator inside the ETC. The experiments were accomplished in three modes namely, ETC without turbulator (Simple-ETC), ETC with coiled turbulator (CT-ETC) and ETC with matrix turbulator (MT-ETC). The results were compared and analyzed. The major results revealed that the presence of the turbulators significantly enhanced the ETC tube mean temperature by stimulating turbulence. They simultaneously improved the solar gain and thereby, mean tank water temperature was boosted-up. Quantitatively, the tank water temperature was escalated by 3.5 °C and 7.5 °C, with the aid of coiled turbulator and matrix turbulator, respectively. Further, the matrix turbulator seems ahead in improving heat transfer inside the ETC compared to coiled turbulator.

Study on an ETC solar water heater using flat and wavy diffuse reflectors

In recent days, evacuated tube (ETC) solar water heating systems are proposed to be the prominent solution for the residential as well as industrial water heating needs of various capacities, without depending on the electrical grids. They serve hot water economically, and independently. However, the efficiency of the water heater is a main concern, especially on the days having low solar insolation and on rainy days. In addition, the underneath of the evacuated tubes is usually not exposed to the direct sunlight and become inactive, which further diminishes the performance of these water heaters. Hence, it is the hot topic of research to improve the performance of these water heaters with the aid special arrangements. In this paper, an experimental assessment is presented to improve the performance of the evacuated tube solar water heater using two different forms of diffuse reflectors, namely flat diffuse reflector (FDR) and wavy diffuse reflector (WDR). The results evidenced that the use of diffuse reflectors enhanced the tank water temperature during the day time, significantly. Further, it was discerned that the tank water temperature was enhanced by 4 °C and 6 °C respectively, with the aid of flat diffuse reflector and wavy diffuse reflector. Comparatively, the wavy diffuse reflector improved the water temperature by 2 °C higher than the flat diffuse reflector.

Investigation on ETC solar water heater using twisted tape inserts

The solar water heaters are finding their application in a number of sectors such as, residential buildings, processing industries, commercial establishments. They can be scaled based on the requirements. Among the different kind of solar water heaters, all-glass evacuated tube type (ETC) solar water heaters are considered to be the better choice for the most applications due to their efficient operations with simple design constraints compared to other type of water heaters. However, there is a large scope to boost-up the performance of the ETC type solar water heaters to the next level with the appropriate modifications in the evacuated tubes, which will help to advance the overall efficiency. The present work proposes the amalgamation of twisted tapes within the evacuated tubes (ET) of the ETC solar water heaters to attain the enhanced performance of the system. The twisted tapes with two different twist ratios of 2 and 3 were used for the investigations. The twisted tapes were made-up of copper tapes of width 15 mm. The experimental trials were conducted on a passive flow ETC solar water heater on the days having alike solar insolation and ambient conditions in three different modes namely, ETC water heater without any twisted tapes (ETC-Plain), ETC water heater with twisted tapes comprising twist ratio of 2 (ETC-Twist 2) and the ETC water heater with twisted tapes comprising twist ratio of 3 (ETC-Twist 3). The results evidenced that the twisted tapes helped to improve the evacuated tube temperature and the tank water temperature of the ETC type solar water heater. The efficiency of the ETC type solar water heater was enhanced by 6.8% and 4.6%, respectively using twisted tapes comprising twist ratio of 2 and 3. Furthermore, the twisted tape with smaller twist ratio was determined to be efficient in improving the performance of the ETC type solar water heater.