Water Heating Purposes Research Articles

Experimental study and semi-empirical model of a thermostatic expansion valve of a R290 direct-expansion solar heat pump

The expansion device plays a crucial role in the operation of heat pumps and refrigeration systems, making its study integral to advancements in the fields of refrigeration and heating. Among various expansion devices, the Thermostatic Expansion Valve (TEV) stands out due to its rapid response time and mechanical nature, which grants it high control capacity over refrigerant superheating. In this study, was developed a semiempirical mathematical model for a TEV incorporated in a DX-SAHP utilizing R290. The research was carried out in an experimental way, conducted using a fully instrumented DX-SAHP. A series of experiments tested different operational modes for water heating, subject to varying solar radiation intensities. A uniform methodology collected operational parameters, resulting in 150 experiments. The semiempirical model creation involved combining basic equations from the literature describing TEV operation and formulating an equation using multiple linear regression based on experimentally evaluated parameters. These parameters included solar radiation incidence, inlet and outlet pressures, and superheating degree. The regression model achieved an adjustment higher than 96 %. Combining this regression with equations suggested by previous researchers, resulted in a model with an adjustment exceeding 94 %. Furthermore, this study culminated in the derivation of a generalized model primed for broad application across various heat pump configurations for water heating purposes. Notably, the model underwent rigorous validation across a separate set of experiments, reaffirming its reliability and versatility. While excelling in steady-state operations, the model's transient data analysis falls short, as intended.

Comparative analysis of solar heaters and heat exchangers in residential water heating

This research shows the comparative analysis between the solar heater and the heat exchanger efficiency. This is used for water heating in this project to show the use of this for residential purposes. The efficiency of these two is calculated in this project which helps to know the efficiency of each model in the water heating purpose. In this research process, a suitable set of comparisons has been drawn between the heat exchanger and water heater that have been worked on based on the effective solar energy. Effective energy usage provides a suitable beneficial impact in Favor of using this residential water heating system of heat exchangers. Detailed information has been represented in the background sections along with rationale aspects where the issues along with their remedies have been depicted.

Spiral tube solar water heating computational analysis with concrete absorber: A CFD approach

Solar collectors with concrete absorber provide structural, aesthetic, and economic advantages over existing common technology. An inexpensive concrete solar collector is being considered to improve the efficiency of solar water heaters (SWH). This work mainly focuses on the analysis of the compact concrete absorbers for water heating purpose with the spiral tube arrangement using solar energy. Concrete absorbers that use straight tubes, while less performance, they are possibly more cost-effective than traditional flat-plate collectors. The flow analysis is to be evaluated ranged between 0.005 and 0.01 kg/s for various water flow rates on the inside of the spiral tube. Furthermore, it is anticipated how the temperature of the water at the exit and storage will behave in respect to solar radiation. A finite volume package ANSYS FLUENT 15 is used to investigate the characteristics of the flow over a SWH's duct. At the lowest mass flow rate, it is discovered that the typical concrete and sand absorber water temperatures are 70 °C and 75 °C, respectively.

Performance Simulation of Solar Trough Concentrators: Optical and Thermal Comparisons

The solar trough concentrator is used to increase the solar radiation intensity on absorbers for water heating, desalination, or power generation purposes. In this study, optical performances of four solar trough concentrators, viz. the parabolic trough concentrator (PTC), the compound parabolic concentrator (CPC), the surface uniform concentrator (SUC), and the trapezoid trough concentrator (TTC), are simulated using the Monte Carlo Ray Tracing method. Mathematical models for the solar trough concentrators are first established. The solar radiation distributions on their receivers are then simulated. The solar water heating performances using the solar trough concentrators are finally compared. The results show that, as a high-concentration ratio concentrator, the PTC can achieve the highest heat flux, but suffers from the worst uniformity on the absorber, which is only 0.32%. The CPC can generate the highest heat flux among the rest three low-concentration ratio solar trough concentrators. Compared with the PTC and the CPC, the TTC has better uniformity, but its light-receiving ratio is only 70%. The SUC is beneficial for its highest uniformity of 87.38%. Thermal analysis results show that the water temperatures inside the solar trough concentrators are directly proportional to their wall temperature, with the highest temperature rise in the PTC and the smallest temperature rise in the TTC. The solar trough concentrators’ thermal deformations are positively correlated to their wall temperatures. The radial deformation of the SUC is much larger than those of other solar trough concentrators. The smallest equivalent stress is found in the SUC, which is beneficial to the long-term operation of the solar water heating system.

Pengatur Suhu Otomatis Pada Solar Water Heater Berbasis IoT

Humans in everyday life really need energy. Energy use is expected to be sustainable, safe and clean. Solar is a renewable energy source that sustains life on earth, it can be utilized through photovoltaic and solar thermal systems. Solar thermal systems that capture solar energy can be used directly for water heating purposes. So that an environmentally friendly water heater can be created. This water heater is a solar water heater. Another problem is that the temperature setting for hot water is still manual, causing waiting time and wasted energy when mixing water is not according to your wishes and needs. The solution requires an automatic temperature regulator is needed on a solar water heater. The DS18B20 temperature sensor is used to read the water temperature, the Wemos D1 R2 microcontroller will consider whether the temperature read is appropriate or not according to the user wishes. If it is not suitable, it will instruct the relay to be active and turn on the water pump to circulate water to the heating collector. Setting the desired temperature can be done remotely using Internet of Things technology. From the results of testing the tool, the solar water heater that has been made is capable of providing hot water temperatures of 50.25 °C, 46°C, 43.12 °C when the tank contains 10 liters, 20 liters and 30 liters of water. The set point setting was successfully done using the blynk platform

Control optimization of PV powered electric storage and heat pump water heaters

Domestic rooftop photovoltaic (PV) systems are typically installed without energy storage and power generated in excess of the building electric load must be exported to the grid or curtailed. In this paper the use of excess PV electricity for water heating is investigated, with the hot water storage tank acting as a low-cost thermal battery. A 3.6 kWp PV system installed on a domestic house with a 315 L storage hot water heater is analysed. It is shown that advanced control of the water heater is critical to make effective use of local intermittent PV power. Without appropriate controls the excess PV power can only reduce the grid energy consumption of an electric storage water heater by approximately 13%. However, with appropriate control, savings of purchased grid electricity above 80% can be achieved for electric storage water heaters. Similarly, using a heat pump, the consumption of purchased grid electricity for water heating can be reduced by close to 90% by making use of excess PV power. The use of excess PV electricity for water heating purposes can also significantly reduce export PV electricity, thereby also assisting the voltage and frequency stabilisation of the electrical distribution network.

Experimental validation of new approach for waste heat recovery from combustion engine for cooling and heating demands from combustion engine for maritime applications

Abstract Waste heat recovery is one of the crucial and fundamental issue of energy management related with energy efficiency improvement, fuel savings, and reduction of greenhouse gases emissions. The paper provides with the experimentation of the prototype heat recovery system dedicated to the small and mid-sized maritime combustion engines of the nominal load of 100–250 kW. The waste heat recovery system is covering the innovative low-pressure steam indirect heat transfer subsystem. The recovered heat is consumed by a heating system and a prototype heat driven ejector refrigeration cycle operating with environmentally safe refrigerant. It was demonstrated that the refrigeration system produces up to 30 kW of cold by consuming 75 kW of heat gathered from flue gases. This is the first prototype of the compact heat driven refrigeration system for marine applications. The waste heat recovery system additionally provides with approximately 60 kW heat recovered from water jacked cooling of the engine block which is used for heating capacity dedicated for tap water and space heating purposes. This covers almost all small and mid-sized vessels needs for thermal energy. The prototype design has been approved by two independent maritime classification societies.

Dynamic simulation and economic analysis of a combined solar thermal and pellet heating system for domestic hot water production in a traditional Hammam

The combination of solar heating systems and low emission biomass boilers provides the opportunity to produce domestic hot water in large applications (multi-family houses, public sector, hotels, schools, etc) without the use of non-renewable energy. However, such systems are not yet widespread in Morocco, since traditional wood-fired boilers are still extensively used for water heating purposes in various applications. Therefore, the objective of this work is to evaluate the thermal performance and economic viability of a combined solar thermal and pellet heating system for hot water supply, designed for a public bathhouse under the climatic conditions of Marrakech, Morocco. Moreover, this paper presents the first small-size parabolic trough collectors installation designed for covering part of the hot water requirements in Morocco. In addition, the potential benefits of using such a system are discussed. The dynamic simulations were performed using models developed using TRNSYS 18 energy simulation software. Furthermore, we examined the effect of different system configurations on the thermal performance of the combined solar thermal and pellet heating system. The performance indicators such as solar fraction, solar system efficiency, collector efficiency and primary energy savings, are used for comparing the energy savings and the performance of these different heating systems. Besides, the life cycle cost method was carried out for the financial analysis by comparing the annual life cycle savings for the combined solar thermal and pellet heating against the conventional system (only biomass). The results presented in the current study indicate that adding solar thermal collectors to the biomass system is economically favorable. The lowest life cycle cost of the combined system was obtained with a collector area of 288 m2, which resulted in a solar fraction of 58%. In addition, an annual life-cycle savings of 5,593 € can be achieved compared to biomass boiler system taken as a reference. Moreover, up to 234 tons of CO2 emissions have been avoided through the use of the combined system. Environmentally, this system can be an attractive option for Morocco where wood energy is widely used for the production of hot water in traditional Hammams. The use of such combined solar and biomass systems may result in significant energy savings and CO2 emission reductions as well as limited deforestation in Morocco.

Gas demand in the Swiss household sector

ABSTRACT In this article, we analyse the gas demand of Swiss households and provide an estimate of the own price elasticity. We use household-level panel data from 2010 to 2014 for 958 Swiss households while controlling for several socioeconomic characteristics and dwelling attributes. The results report the own price elasticity of gas demand to be around – 0.73. An inelastic demand is expected as the gas demand among Swiss households originates primarily for space heating and water heating purposes. Policy implications are discussed.

Trade-off working fluid selection for heat pumps

Nowadays heat pump systems are used to recover the heat from waste water from different sources and produce hot water for household and communal purposes. In this research comparative thermodynamic analysis of performance for a water-to-water single-stage vapor compression heat pump using several HCs, HCFCs and HFCs which belong to refrigerants of different generations is presented. A multi-criteria approach for optimal selection of refrigerants was used as scientific tool. Results of theoretical experiments of vapor compression heat pump system with the evaporator temperature range 0…25°C and condenser temperature 60°C and 83°C showed that the COP of R1234ze was higher than that of R600a, R152b by about 6.7…17.3%, 8.25…20.5%, and 1.7…14.4%, respectively, at condenser temperature 60 °C; however results are different if at condenser temperature is 83°C: the average COP of R600a was higher than that of R1234ze and R152b by about 7.7…14.7%, 9.3…15.8%, and 7.5…15.6%, respectively. COP displays a positive correlation with the evaporator temperature as well as a negative correlation with the condenser temperature. The complete analysis of all factors, including environmental safety, indicates that R1234ze and R600a refrigerants should be preferred as the working fluids for using in the water-to-water single-stage vapor compression heat pump for the hot water supply and heating purposes in industrial applications.

The efficiency of improvising cooling operation by introducing Phase Changing Material (PCM) as an insulator – A review

Our project deals with the fabrication of a battery performance using Phase Changing Material (PCM). No being can live without water and food. To cook the food or to heat the water heat energy is required. In the present scenario, to get the heat energy, liquefied petroleum gas, kerosene etc. are being used as fuel. These fuels are highly expensive. Battery storage system energy can be used for water heating purposes. Battery storage system energy is available almost everywhere and is well economical too.The Battery stockpiling framework water warmer utilizing PCM is created so that it tends to be utilized for putting away warmth vitality just as for warming water. This sort of Battery stockpiling framework water warmer can be utilized in zones where daylight is accessible, all over. This water radiator can be utilized for quite a while and the cost engaged with assembling this warmer is low, so that even a little family or a typical man can bear the cost of it.

Thermal performance analysis of a co-axial evacuated tube collector with single and two-phase flow consideration under North-eastern India climatic condition

The standard condition for evaluation of solar heating system considers solar insolation of 1000 W/m2 which provides a good estimation of the performance of the system, but not able to predict a realistic situation due to the fluctuating behaviour of solar insolation. Therefore, an attempt is made to simulate a practical condition for a solar heating system by varying solar radiation throughout the day as well as months of a year. Hourly solar insolation data are collected from web-based resource PVGIS for the region of Silchar, a north-eastern location in India. The results revealed that the temperature profile of the working fluid in the Evacuated Tube Collector is non-linear and the rise in temperature is more in the months of November-March than April-October. The outlet temperature is highest for the month of February and lowest in June which signifies that the system can be practically applicable in this region for water heating purpose, as it produces a higher temperature in winter days. Also, the daily analysis shows the efficiency of the system is very low during the morning and evening hours. Moreover, there is a possibility of obtaining a two-phase flow in the outer pipe under certain circumstances and this production of vapour is accompanied by a reduction in efficiency. The analysis shows that with radiation being fixed, inlet temperature and mass flow rate are the most dominant factors for two-phase flow. Present model also suggests an optimum mass flow rate beyond which the flow becomes two-phase and not desirable.

Transient analysis with coupled field-circuit model and experimental assessment of a PMSG used in small-scale wind turbine for water heating purpose

This paper introduces the detailed coupled field-circuit analysis including performance characteristics of a 4-kW in-running rotor permanent magnet synchronous generator (PMSG) used in rural-type small-scale wind turbines for water heating purpose. The content of the work consists of design, analysis, optimization, production and testing processes and validation studies. An integrated 2D electromagnetic field and circuit model are used in the design and analysis processes. The electrical machine design involves complex and time-consuming processes. This model provides comprehensive information on machine behavior under different conditions and is an effective to demonstrate compliance with real load conditions prior to the manufacture. The goal of the optimization process is to find a design that offers cost, manufacturability and efficiency as well as generator output values. For this, a multiobjective optimization approach has been used. Typical design and simulation principles are applied to the designed PMSG, respectively, including calculation and evaluation of various output parameters for different simulated wind speed rates and varying load conditions. Furthermore, the analytical studies related to finite element methods and parametric approaches are presented in collaboration with experimental studies carried out for different load rates.

Design and Fabrication of Solar Water Heater with CPC by using Wafers Packet

The objective of our project is to create a system which can heat water at maximum temperature and give more efficiency than the current system used in the market today for daily water heating purpose and also less costly which is the main factor. So we made a prototype system of less expensive material and another main material such as wafer packet which will absorbs more sunlight. The evacuated collector for natural circulation discharge through single ended water-in-glass evacuated tubes mounted over a diffuse reflector was also taken into consideration. Therefore, the concept of Compound Parabolic Collector (CPC) is used to heat the water and with a small aperture area as compared to other collectors is possible to achieve a maximum water temperature up-to 100°C. The system is of reasonable cost as compared to existing ones. Collector efficiency is nearly 65%, however if all the control about reflecting rays and insulation is used for reducing the heat loss may be efficiency increasable comparably.

Thermal capacity: Additional relative efficiency to assess the overall performance of heat pump-based heating systems

The present analytical study is carried out to introduce the thermal capacity, a relative efficiency based on a different approach, to assess the performance of heat pump-based systems. Through the first law of thermodynamics and the universal heat transfer coefficient, the heat yielded by the heat pump and the thermal load demanded by the product are quantified respectively, consequently determining the heat transfer capabilities of the system. This performance metric was tested using experimental data published on different researches using four distinct setups, working under various geographical and climatological conditions and for both indoor air conditioning and water heating purposes. Since the parameter introduced was developed as a complement to the already existing relative efficiencies, when combined with the coefficient of performance, COP, a region of minimum required performance is created, where the heat pump is expected to operate, being able to fulfill the energy demand of the product while maintaining an acceptable performance. Finally, the information provided by the thermal capacity was found to be useful regarding the design and operation of these systems due to its conditional nature, enabling the operator or decision maker to assess categorically the performance and to propose modifications to the heat pump system accordingly.

Performance Estimation of Solar Flat Plate Air Heating System Using Helical Tapes

Solar flat plate collectors (FPC) are used for heating spaces, water heating, and many other purposes. The present technology of solar flat collectors uses vertical fins. The solar flat plate collector having absorber with vertical fins is provided with a helical tape in the fluid flow path. The absorber plate in the solar flat plate collector has an area of 100 cm x 50 cm. The solar flat plate collector has nine ducts with an area of 27.5 cm x 9.5 cm each. The helical tapes attached have a start angle of 64 deg which pass along the whole length of the duct. The helical tapes have a crosssection area of 1.5 mm x 4 mm. The pitch of the helical tapes is 100 mm. These fins have been attached between the vertical fins of the thickness of 1mm and a height of 10.5 cm. Data such as inlet temperature, outlet temperature efficiency and convective heat transfer coefficient are calculated. The mass flow rate of air is 10.28 kg/s and the air is subjected to solar radiation between 628.98 W/m2 and 708.59 W/m2. The values are noted down, and the and the efficiency is noted to have a 10% rise. The effectiveness of the solar plate collector will increase using a helical fin. A comparative analysis will be done between the conventional flat plate collector and the setup with the helical tapes. The study will show that the helical tapes in flat plate collector will be the best alternative compared to conventional flat plate collector.

Thermal performance of a solar latent heat storage unit using rectangular slabs of phase change material for domestic water heating purposes

In this paper, the thermal performance of a rectangular latent heat storage unit (LHSU) coupled with a flat-plate solar collector was investigated numerically. The storage unit consists of a number of vertically oriented slabs of phase change material (PCM) exchanging heat with water acting as heat transfer fluid (HTF). During the day (charging mode), the water heated by the solar collector goes into the LHSU and transfers heat to the solid PCM which melts and hence stores latent thermal energy. The stored thermal energy is later transferred to the cold water during the night (discharging process) to produce useful hot water. The heat transfer process was modeled by developing a numerical model based on the finite volume approach and the conservation equations of mass, momentum, and energy. The developed numerical model was validated by comparing the simulation results, obtained by a self-developed code, with the experimental, numerical and theoretical results published in the literature. The numerical calculations were conducted for three commercial phase change materials having different melting points to find the optimum design of the LHSU for the meteorological conditions of a representative day of the month of July in Marrakesh city, Morocco. The design optimization study aims to determine the number of PCM slabs, water mass flow rate circulating in the solar collector and total mass of PCM that maximize the latent storage efficiency. The thermal performance of the LHSU and the flow characteristics were investigated during both charging and discharging processes. The results show that the amount of latent heat stored in the optimum design of the storage unit during the charging process is about 19.3 MJ, 16.54 MJ, and 12.79 MJ for RT42, RT50, and RT60, respectively. The results also indicate that depending on the mass flow rate of HTF, the water outlet temperature during the discharging process varies within the temperature ranges 43.6 °C-24 °C, 51.7 °C-24 °C, and 62.86 °C-24 °C for RT42, RT50, and RT60, respectively.

1D model for a low NOx ejector-pump like burner

This work is about a model for the prediction of air entrainment in a full-premix, atmospheric, ejector-pump like gas burner, used for domestic water heating purposes. The model improves current knowledge by including the effects of combustion and buoyancy on the air entrainment mechanism. It predicts the λ ratio (excess of air in relation to stoichiometry) as a function of ambient conditions, burner geometry, type of hydrocarbon fuel and burner firing rate. A prototype burner with variable geometry was assembled to calibrate and validate the model. The combustion products were analyzed with a CO2 sensor and the λ ratio was compared with model’s predictions, showing good accuracy. A parametric study was done to ascertain the impact of key geometric parameters on burner aeration.

Experience and Prospects of Water Heating Using PV Panels

The paper deals with the photovoltaic panels application for water heating purposes. We have developed and tested the mathematical models for traditional and PV-based water heaters. Modeling shows that the area ratio for PV-based and collector-based water heaters with close productivity is about 1.6–2.3 for Russian southern regions and 1.2–1.6 for northern ones. PV-based water heating systems are shown to have several advantages compared to collector-based ones, including close capital costs in Russian conditions and simpler installation and operation, especially in northern regions of the country. The paper classifies the commercial controllers for PV-based water heating systems. Modern commercial PV water heating systems are supplied with maximum power point (MPP) tracker technology controllers. Cost for such special controllers is quite high, and several manufacturers make them. The most of manufacturers consider PV water heating systems as a part of “smart home” or way to utilize excess of energy produced by PV array. Thus, the researches of possible improvement and cost decrease for PV water heaters are actual. It is shown that the possible way to simplify and make cheaper the whole PV water heater is to make it without controller but to use constant resistance element as electric load. In this case, PV array productivity decrease can be compensated by additional PV panels in the array, and the year heat production is higher than for collector-based system with comparable capital cost.

Experimental Study of Two Different Types of Solar Dish Characteristics and its Efficiency Based on Tikrit, Iraq Weather Conditions

Two solar dish concentrators (SDC) with diameter of (2 m) have been designed for water heating purpose. This study applied on solar steam water heater (SSWH). Both of the dishes coated with thick layer of steel (galvanized), while its interior surface covered with a reflector layer. The first dish interior surface covered with a layer of reflectivity up to 80%, whereas the second one covered by a pieces of mirrors with a reflectivity of 95%. The receivers have been fixed in the focal position of both dishes. The measurement of temperature and solar power for both types have been documented and recorded. The optical energy for the 1st dish is 1909 W, the final energy is 1551 W, and the efficiency is 61 %, while the optical energy for the 2nd dish is 1607.68 W, the final energy is 1853 W, and the efficiency is 73 %. The obtained results affirmed that the materials used in this research are economic, with high quality to obtain solar concentrator, but the dish which is covered with pieces of mirrors is better, and it can be used for water heating.