Domestic Water Heating Research Articles

Investigation on the Combustion Characteristics and Environmental Effects of Hydrogen-doped Natural Gas for Domestic Water Heaters.

The addition of hydrogen to natural gas is an effective approach to broaden the range of applications for hydrogen and address the issue of global warming. However, the inclusion of hydrogen alters the combustion properties of natural gas. The paper established a simplified mechanism consisting of 19 components and a 67-step reaction for hydrogen-doped natural gas combustion. With this simplified mechanism, the effects of hydrogen doping and the utilization of porous media combustion techniques on the combustion characteristics of natural gas were investigated numerically. The results suggested that the utilization of porous media combustion technology is beneficial for achieving the complete combustion of hydrogen-doped natural gas and reducing pollutant emissions. Additionally, the total gas cost and environmental impact of domestic gas water heaters with hydrogen-doping natural gas were estimated. The findings show that the use of 20% hydrogen-doped natural gas contributes to a decrement in fuel costs and reduced emissions of CO by 25.4%, NOX by 53.9%, and CO2 by 6.78%.

The potentials of thermal energy storage using domestic electric water heater technology with PV systems in the EU countries

Recently, there has been a considerable decrease in photovoltaic technology prices (i.e. modules and inverters), creating a suitable environment for the deployment of PV power in a novel economical way to heat water for residential use. Although the technology of TES can contribute to balancing energy supply and demand, only a few studies have investigated its potentials. These days, TES technology can play a significant role in mitigating the negative network effects resulting from higher proportions of electricity generated by PV systems. The presented research examined the possibility of applying a new technological direction in connection with PV utilization in the European Union (EU), with a view to promoting the spread of cost-effective energy storage and increase energy independence. The purpose of this study was to examine the deployment of combined TES and PV systems in the EU countries by the example of a special 3.5 kW inverter and a 200-l domestic electric water heating system. The innovative significance of the research is that it explores this practical solution, by determining the seasonal energy saving potentials of the application of this sensible heat storage method in the context of all the EU countries.Graphical HighlightsThe recent extraordinary increase in installed photovoltaic (PV) capacity cannot be successful without integrating it with energy storage (ES) to store generated surplus power to be consumed later.Technological developments and the trend of falling PV module and inverter prices makes it possible to apply economical solutions for hot water production for domestic hot water use and/or assisting space heating, based on the use of solar energy.The combination of modern inverter technology, PV and domestic electric water heating systems provides a storage solution for PV energy with considerable cost saving potentials in the countries of the EU.Many factors influence the ideal and economical size of such combined systems and their components, which need careful consideration and calculation.For a better utilization of the potentials offered by this new solution more complex analyses and the investigation of the ways of linking thermal energy storage (TES) and PV systems and possibly other technologies is necessary.DiscussionHow can the efforts to decrease the household consumption of energy used for heating water and space heating connected to the issue of integrating variable renewable energy sources into energy systems?How can currently commercially available technology be used for storing electrical energy generated by photovoltaic systems in the form of heat energy?What determines the potential energy and costs savings achieved by a combined system of a small photovoltaic power plant and a home electric water heating system for the households in the various countries of the European Union?What are the potentials of the suggested system in terms of energy and costs savings in the context of households in the EU countries?

PCM-based domestic solar water heating in Malaysia: Setbacks and countermeasures

Solar water heating (SWH) systems have yet to be widely employed despite their promising features for hot water production, especially in rural areas. This paper discusses several setbacks to the implementation of SWH systems. Generally, the setbacks are related to weather issues, the collector’s technical damages, and financial constraints. A few potential countermeasures to these setbacks are also listed.

Artificial neural network model for predicting CO2 heat pump behaviour in domestic hot water and space heating systems

The natural refrigerant, CO2, possesses thermophysical properties that make it highly suitable for domestic hot water (DHW) production using heat pump technology. In this study, the development and validation of an artificial neural network (ANN) model that enables efficient design and control of a CO2 heat pump is presented. The study employs experimental data from a CO2 heat pump with a nominal heat capacity of 8 kW. The fully instrumented rig includes the heat pump and a pump rig designed to generate system temperatures representative of various space heat and DHW demands. A comprehensive dataset was generated through systematic variation of inlet temperatures and setpoints. The ANN provides predictions for outlet temperatures, heat production, and electricity consumption utilizing inlet flow rates, temperatures, and setpoints as inputs. These predictions are important for condition monitoring or in a smart operation management framework that determines optimal schedules for the machine.

TRNSYS MODEL OF THE COMBI BOILER DOMESTIC HOT WATER CIRCUIT WITH A FOCUS ON THE PARAMETER DEFINITION OF THE PLATE HEAT EXCHANGER

Combi boilers used for both space and domestic hot water heating are one of the common household appliances. Modelling the domestic hot water circuit of a combi boiler for the preliminary evaluation of the laboratory testing is of crucial importance since it decreases the time, cost, and energy spent on the trials. There are various modelling approaches established by the authors of this paper. Domestic hot water circuit of the appliance is modelled previously making use of the Transient System Simulation Tool (TRNSYS 18) and a good agreement is achieved with the experimental and numerical data for the economic mode simulations. The drawback of the current TRNSYS model is the dependence on the experimental data for some of the parameter definitions of the components selected from the TRNSYS library, i.e. UA (multiplication of the overall heat transfer coefficient and the heat transfer area) input of the plate heat exchanger and heat retention effect of the heat cell block. In this paper, a constant value is assigned to the parameter definition of UA instead of a time dependent varied profile. Mean absolute errors covering the steady-state and transient operating regions for the domestic hot water inlet and outlet temperature difference in economic mode simulations stay nearly the same around 0,46°C, 0,82°C, and 0,53°C for 5 l/min, 7 l/min, and 8,7 l/min, respectively, under constant and variable UA approaches. Comfort operating scheme model is established with a couple of experimental data as of the principal application of the constant UA approach. Mean absolute error of the overall domestic hot water inlet and outlet temperature difference profile decreases to 0,5°C in the comfort mode simulation.

Simulation Research on the Optimization of Domestic Heat Pump Water Heater Condensers

To improve the heat transfer coefficient of a condenser, this paper proposes using a fin-tube condenser to replace a smooth-tube condenser in a domestic heat pump water heater. The finite element method is used to analyze the heat transfer coefficient of fin-tube condensers with different design parameters. By comparing the results of experiments with those obtained using CFD methods, it has been determined that the CFD method used in this study is feasible. Simulation results showed that the heat transfer coefficient enhanced clearly. The total thermal resistance of the fin-tube condenser decreased by 7% through increasing fin thickness. The total thermal resistance of the fin-tube condenser increased by 1–1.3% when fin spacing was increased. The heat transfer coefficient decreased severely and the maximum total thermal resistance of the fin-tube condenser increased by 8.7% with increasing fin height. In 600 s, when the fin spacing, fin height, fin thickness and inner diameter were 14 mm, 12.5 mm, 1.2 mm and 22.5 mm, respectively, compared to the smooth-tube condenser, the fin-tube condenser could increase the final water temperature by 18.37%, and the heat transfer coefficient would increase by about 95%. This research could provide a low-cost way to improve the heat transfer coefficient of condensers in domestic heat pump water heaters.

Optimal control of a solar-driven seasonal sorption storage system through deep reinforcement learning

Deep reinforcement learning (DRL) has demonstrated its effectiveness in the control of energy systems, although it has not yet been applied to sorption thermal energy storage (TES) systems. The operation of sorption TES systems is notably more complicated compared to other TES variants. The discharge of a sorption TES occurs at a particular desorption and evaporation temperature. Achieving a continuous and efficient discharge of a sorption TES is a challenging control task if heat required at the evaporator is obtained from the sun or the environment. Its operation is especially complicated during winter, because of the limited availability of solar irradiation and low ambient temperatures. Thus, this study analyzes for first time in the literature the competitiveness of deep reinforcement learning to control a solar-driven seasonal sorption TES system and compares it against traditional optimized rule-based control strategy. The system, located in Central Europe, supplied domestic hot water and space heating to a single-family house. Two DRL models were developed and trained to operate the system under two different sets of data: 120 winter consecutive days and 60 winter non-consecutive days. The results showed that the DRL control strategy reduced the system operational costs by 28% in a 60 winter days scenario. For a 120 winter days scenario, the operational cost savings decreased to 13% because the smart control performed worst once the sorption TES was fully discharged. These results were derived from a four-year validation data set, bolstering their robustness. The study demonstrates the successful application of DRL in controlling a solar-driven seasonal sorption TES system, yielding considerable economic savings compared to an RBC strategy. Subsequent work will consist of implementing the smart control strategy at prototype level to assess its performance.

Modeling and comparative assessment of solar thermal systems for space and water heating: Liquid water versus air-based systems

This work pertains to the transient modeling and comparative study of active solar thermal space and water heating systems using liquid and air-type solar thermal collectors as the main energy source. The study utilizes TRNSYS to simulate the two systems in the context of Taxila's weather data (located at 33.74°N, 72.83°E), with the goal of meeting peak space and domestic water heating demands of 20 kW and 200 lit/day, respectively. The liquid water-based system (S-1) is primarily composed of a liquid solar collector, thermal storage, an auxiliary heater, connections to the hot water supply, and the space heating load through a water–air heat exchanger. In contrast, the air-based system (S-2), employs a pebble bed storage to store heat extracted from the solar thermal air collector. The heated air is subsequently used directly for space heating and passed through an air–water heat exchanger for water heating. Dynamic simulations of both systems span the entire winter season, and various performance metrics, including solar fraction, primary energy savings, and solar collector thermal efficiency, are computed. The results revealed that at the same collector area, the liquid water-based system (S-1) shows a higher solar fraction than the air-based systems (S-2) while the primary energy savings of the S-1 resulted in lower values than S-2 at smaller collector areas (< ∼30 m2) but surpasses the S-2 with increasing collector size. The optimal collector tilt for both systems is determined to be 50°, while specific storage volumes corresponding to maximum primary energy savings are estimated to be 100 and 40 L/m2 for S-1 and S-2, respectively.

Rational Use of Energy in Sport Centers to Achieving Net Zero—The SAVE Project (Part B: Indoor Sports Hall)

Sports centers are significant energy consumers. This article outlines the engineering design for a comprehensive energy performance upgrade of the indoor sports hall in Arkalochori, Greece, and presents the projected results. The indoor sports hall constitutes a major sport facility on the mainland of Crete, hosting a broad cluster of sport municipal activities and the official basketball games of the local team in the 2nd national category. Having been constructed in the mid-1990s, the facility exhibits very low thermal performance, with considerably high U-factors for all constructive elements (from 4 to 5 W/m2∙K), still use of diesel oil for indoor space heating and domestic heat water production, and ineffective old lamps and luminaries covering the lighting needs of the facility. The energy performance upgrade of the indoor sports hall was studied, and the following passive and active measures were considered: Opaque-surfaces’ thermal insulation and openings’ replacement, stone wool panels, installation of heat pumps for indoor space conditioning, removal of diesel oil for any end use, production of domestic hot water from a novel solar-combi system, upgrade of lighting equipment, installation of solar tubes on the main sports hall roof for natural lighting as well as of a photovoltaic system for covering the remaining electricity consumption. With the proposed interventions, the studied building becomes a zero-energy facility. The payback period of the investment was calculated at 26 years on the basis of the avoided energy cost. This work was funded by the “NESOI” Horizon 2020 project and received the public award “Islands Gamechanger” competition of the NESOI project and the Clean Energy for EU Islands initiative.

Blend of flue gas from a methane-fueled gas turbine power plant and syngas from biomass gasification process to feed a novel trigeneration application: Thermodynamic-economic study and optimization

Enhancing the stability and cost-effectiveness of gas turbine power plants while mitigating input costs, co-feed arrangements, and multi-heat recovery processes shows great promise. The present study introduces an innovative trigeneration application to energetically and economically modify the existing gas turbine cycle. This trigeneration system incorporates several components, namely a helium gas turbine power plant, a regenerative steam Rankine cycle, a domestic water heating unit, and a multi-effect desalination subsystem. The thermodynamic and economic factors were considered to assess the performance indexes. Furthermore, a thorough technical analysis was conducted on the thermodynamic and economic variables, considering the influence of five crucial decision-making factors. Also, the operation mode of the system was optimized through multi-objective optimization of power and heating load. The outcomes of this optimization process revealed that the optimal values for electric power and heating load are 507.34 kW and 261.94 kW, respectively. Additionally, the capacity of freshwater obtained of about 0.076 kg/s. The optimal solution also showcased an exergy efficiency of 44.93 % and a relatively short payback period of 4.68 years, indicating the system's cost-effectiveness and favorable performance.

Data-driven predictive control for demand side management: Theoretical and experimental results

Demand side management is perceived as a tool to support a secure and reliable energy system operation amid growing integration of renewable energy resources. However, the lack of scalable modeling and control procedures hinders the practical implementation. To address this challenge, this paper proposes a novel signal matrix model predictive control algorithm. Compared to existing data-driven methods, this approach explicitly provides stochastic predictions considering both disturbance and measurement errors with few tuning parameters, ensuring reliability by high-probability constraint satisfaction. The performance is extensively compared with three state-of-the-art algorithms in a space heating case study using a high-fidelity simulator. The results are further validated with physical experiments using the same system that the simulator is based on. To assess transferability, the algorithm is further implemented on diverse controlled systems, including a domestic hot water heating system and a stationary electric battery. The simulation results show that, compared to existing data-driven methods, the proposed approach improves constraint satisfaction and energy savings by up to 90 % and 8 %, respectively. The experimental results further confirm that the algorithm is applicable to multiple tasks of demand side management, with reasonable control performance observed in all case studies.

Improved efficiency in an integrated geothermal power system including fresh water unit: Exergoeconomic analysis and dual-objective optimization

The single-flash geothermal cycle (SFGC) is not without its limitations, featuring drawbacks like diminished efficiency, restricted power generation capacity, and the incapability to yield multiple outputs concurrently. Furthermore, the SFGC requires a substantial water supply, potentially leading to adverse environmental consequences. In a concerted effort to enhance overall performance and facilitate the concurrent production of multiple valuable products, this study introduces a multigeneration system (MGS). By integrating additional subsystems into the SFGC framework, including a branched GAX cycle enabled by a thermoelectric generator (TEG), a domestic water heater (DWH), and a reverse osmosis unit, the objective is to surmount these limitations effectively. A thermodynamic and exergoeconomic analysis of the system is conducted and a bi-objective optimization is employed to minimize system cost and maximize exergy efficiency. The parametric study reveals that when degassing ranges are in the range of 0.2–0.37, the system product cost varies from $27.07/MWh to $28.44/MWh. In the optimized scenario there is a decrease of 67.7% in cooling provided by the system. This leads to an increase of 3.5% in generated electricity and a 3% increase in water purification compared to the base scenario. Through optimization the exergy efficiency of the system improves from 61.84% to 62.90% while the multigeneration gain output ratio (MGOR) decreases from 1.40 to 1.38.

Experimental performance of a full-scale solar thermal system designed to meet residential heating demands with passive solar energy

This article presents the results of a 250 day study into a novel mechanical system (called PiSCES) that increases the proportion of residential heating demands that can be met with passive solar energy. PiSCES uses hydronic floor cooling to capture excess solar gains to avoid overheating in highly glazed spaces and this extracted energy is transferred to thermal energy storage (TES) systems via a heat pump. The stored energy can then be used to supply active space heating (SH) and domestic hot water (DHW) heating demands as needed. In the current experiment, active cooling removed 54% of the passive solar gains entering the test house and, of the gains left in the conditioned spaces, 93% were able to offset active heating demands without causing overheating. The excess daytime solar gains collected by PiSCES were used towards active heating demands and resulted in modest solar fractions between 51%–54% for SH and between 30%–39% for DHW demands. The utilization of passive solar gains towards heating demands was increased from 49% to around 70% with the addition of PiSCES to manage and distribute the incoming gains. Although PiSCES, as it is currently configured, was not seen to be a net energy benefit for the test house (the system consumed more electrical energy to operate than the solar energy it was able to resupply), it is suspected that improved TES efficiency, increased TES capacity, and a modified heat pump design could significantly improve performance in future studies.

Comparative capacities of residential solar thermal systems versus F-chart model predictions and economic potential in an equatorial-latitude country

One popular simulation tool for predicting solar thermal (ST) performance is the F-chart model, which has not been validated for the conditions in equatorial-climate countries. In this work, the performance of two ST systems (evacuated tube collectors (ETCs) and flat plate collectors (FPCs), widely used for supplying domestic hot water (DHW) was assessed and compared with F-chart simulation results. The energy demands were simulated by scheduling hot water discharges and measuring the backup energy requirements to fulfil DHW needs. Then, the difference between the calculated solar fraction using the F-chart model and the measured solar fraction was obtained. Both the measurements and simulations showed that the ETC systems performed better than the FPC systems in a city located on the Ecuadorian highlands with distinct climate conditions. The results showed that ETC systems are, on average, up to 18.5% more efficient than FPC systems. A comparative economic analysis was carried out considering that domestic water heating systems are backed up with liquified petroleum gas (LPG) or electricity, both with and without state subsidies. However, due to the higher cost of ETC technology compared to FPC technology, and despite ETC’s higher efficiency than FPC’s, only US$0.34 per month can be saved on average because of the impact of energy subsidies. Thus, the FPC technology seems more profitable, under the mentioned conditions, because of its lower capital costs. With backup systems powered by unsubsidized energy, the two technologies are nearly comparable. The ETC technology appears suitable only under the unsubsidized electricity scenario. The novelty of this research is that real ST systems installed under similar conditions are integrated, the operation of ST technologies for DWH is simulated, and the different inclinations and orientations of solar collectors are considered. The results are compared with simulations from the F-chart model, and each system is economically assessed.

Investigating the annual energy-saving and energy-output behaviors of a novel liquid-flow window with spectral regulation of ATO nanofluids

Building envelopes with energy-generation from renewable sources are highly promising for the green development of buildings. Recently, a new concept of energy-efficient window i.e., the water flow window (WFW), that can capture solar energy for domestic water heating, was reported. However, the output heating capacity of the WFW is inferior due to the limited absorption bandwidth of water. In this study, the ATO-based liquid filled window (LFW) was newly conceived for broadband solar harvesting and effective indoor solar regulation, and then a transient model was developed to figure out the annual performance of ATO-based LFW. By comparing the performance of ATO-based LFW with different ATO concentrations, it was found that an ATO mass fraction of 100 ppm is a positive solution for feasible luminous transmittance about 52%, and excellent monthly output heating capacity between 19 and 60 MJ/(m2·month) in Beijing. With the 100 ppm ATO-based LFW nanofluids, the output heating capacity and the annual solar heat gain coefficient (SHGC) of the ATO-based LFW in four cities with different climatic conditions were discussed. The results indicate that the 100 ppm ATO-based LFW shows the highest level of output thermal energy in Hong Kong, the highest output water temperature in Beijing, the lowest output heating capacity in Harbin, and the lowest cooling energy-saving potential in Chengdu. We believe that the ATO-based LFW is a feasible and applicable solution for achieving carbon neutrality in buildings, especially for buildings in hot regions.

Thermal analysis of a cascaded latent thermal storage tank in a solar domestic water heating system

AbstractTo enhance the thermal characteristics of a solar collector storage system, this study investigates the performance of a rectangular thermal energy storage (TES) tank by incorporating cascade phase change materials (cascade‐PCMs). Three different commercially available PCMs (RT44HC, RT54HC, and RT62HC) with distinct melting temperatures are employed. These cascade‐PCMs are utilized as slabs in vertical rectangular modules, which are integrated into the water TES tank. The heat transfer fluid (HTF) in the flat‐plate solar collector captures solar energy and transfers it to the TES tank, where it is stored as latent thermal energy. A two‐dimensional (2D) numerical model, utilizing the enthalpy‐porosity approach and conservation equations, is developed to analyze the melting and heat transfer processes within the TES tank. The model is validated against previous experimental and numerical data. Performance evaluation of the cascade‐PCMs tank is conducted during a 9‐h charging period (from 8:00 am to 5:00 pm) under Marrakesh weather conditions in Morocco. An optimization study is carried out to determine the optimal height of each cascade‐PCM. The results suggest that an optimal design with heights of 23, 16, and 11 cm for RT44HC, RT54HC, and RT62HC respectively, offers improved melting and storage quality. The thermal characteristics of the TES tank incorporating cascade‐PCMs are compared to those of a TES tank filled with a single phase change material (single‐PCM) during the charging period. The findings indicate that the cascade‐PCMs achieve complete melting, while the single‐PCM only reaches a melting fraction of 0.903 at the end of the charging process. Furthermore, the optimal configuration of the cascade‐PCMs storage tank exhibits slightly higher sensible and latent thermal energy storage capacity compared to the single‐PCM tank. The combination of the solar collector with the cascade‐PCMs storage tank results in a 3.47% higher average collection efficiency when compared to the single‐PCM tank.

Design and Fabrication of Vapour Compression Refrigeration Cycle Based On Storage Type Domestic Water Heater

In present scenario, generally VCR (Vapour Compression Refrigeration) cycle is used for heating and cooling. The adverse effect of release of refrigerant like global warming and ozone depletion in the atmosphere is known to all. Electric heaters use electricity which is obtained from thermal power plant run on fossil fuels. The aim of the project is to demonstrate the economic benefit of using heat rejected in the condenser of Vapour Compression Refrigeration (VCR) system and to check the feasibility of the apparatus for mass production. The main aim of the project is to develop economically viable VCR cycle based domestic water heater (Heat pump) which has a good payback period and low energy consumption compare to electric-resistance heater. To develop storage type water heater, helical coil shaped condenser brazed inside the water storage tank has been designed. Since the capacity of the VCR system is less, capillary tube has been used as an expansion device. The VCR cycle based DWH has been tested extensively and heating capacity of about 725 W has been obtained. This may be due to under sizing of evaporator or condenser or may be due to larger capillary length. The VCR cycle based DWH can save up to Rs. 4770 compared to electric resistance water heater. The simple payback period for DWH is 3 year and 1 month.

Multi-variable assessment/optimization of a new two-source multigeneration system integrated with a solid oxide fuel cell

The integration of renewable energies can improve the thermodynamic performance and increase the popularity and commercialization of the energy production system. Moreover, the exploitation of renewables in the form of cascade energy systems with multigeneration goals has been able to overcome many restrictions and penalties. Meantime, fuel cells are efficient, carbon-free, and promising energy conversion technologies can act as a storage system and improve the sustainability of the energy system. In this article, a new two-source multigeneration system (TS/MGS) based on a biomass fuel and a geothermal source is introduced and evaluated. The upstream process of the considered system is based on a municipal solid waste (MSW)-gasification process-fueled solid oxide fuel cell (SOFC) stack. Besides, the downstream process is comprised of a geothermal source based on a triple-flash cycle, an ejection-based refrigeration process, a water electrolysis cycle, and a domestic water heater unit. The offered TS/MGS is capable of generating electricity, cooling load, heating load, and hydrogen fuel. Converting MSW to energy, in addition to producing efficient energy, can help waste management in urban communities. The operation of the offered TS/MGS was comprehensively investigated from thermodynamic, cost and environmental standpoints. Moreover, the optimal behavior of the TS/MGS is compared under two different decision-making approaches (based on a tri-objective optimization algorithm). Under the considered design parameters, the considered TS/MGS can provide about 3.92 MW of electric power, 2.19 MW of cooling load, ∼ 1.55 MW of heating load, and 0.1 g/s of hydrogen fuel to the consumer (at a thermal efficiency of 33.5% and an exergy efficiency of 61%). The values of total unit cost of products and levelized total carbon dioxide emissions were 0.0211 $/kWh and 0.21 kg/kWh. Under the TOPSIS decision-making approach, relatively more optimal exergoeconomic and environmental outcomes can be achieved compared to the LINMAP decision-making approach. However, the thermodynamic behavior under the LINMAP decision-making approach is more optimal than the TOPSIS decision-making approach.

New Evacuated Tube Solar Collector with Parabolic Trough Collector and Helical Coil Heat Exchanger for Usage in Domestic Water Heating

Buildings represent approximately two-thirds of the overall energy needs, mainly due to the growing energy consumption of air conditioning and water heating loads. Hence, it is necessary to minimize energy usage in buildings. Numerous research studies have been carried out on evacuated tube solar collectors, but to our knowledge, no previous study has mentioned the combination of an evacuated tube solar collector with a parabolic trough collector and a helical coil heat exchanger. The objective of this paper is to evaluate the thermal behavior of an innovative evacuated tube solar collector (ETSC) incorporated with a helical coil heat exchanger and equipped with a parabolic trough collector (PTC) used as a domestic water heater. To design the parabolic solar collector, the Parabola Calculator 2.0 software was used, and the Soltrace software was used to determine the optical behavior of a PTC. Moreover, an analytical model was created in order to enhance the performance of the new model of an ETSC by studying the impact of geometric design and functional parameters on the collector’s effectiveness. An assessment of the thermal behavior of the new ETSC was performed. Thus, the proposed analytical model gives the possibility of optimizing ETSCs used as domestic water heaters with lower computational costs. Furthermore, the optimum operational and geometrical parameters of the new ETSC base-helical tube heat exchanger include a higher thermal efficiency of 72%. This finding highlights the potential of the heat exchanger as an excellent component that can be incorporated into ETSCs.

Energy simulation on how to go green buildings in an earth's dry climate

Green buildings, i.e. low-energy and environmentally-friendly buildings, are highly demanded for optimizing the energy consumption and reducing the Green House Gas (GHG) Emissions. In this study, energy consumption of a residential building is analyzed in the hot and dry climate of Kashan, Iran. This is done based on the criteria of green buildings, using the Design Builder software. Several approaches are presented and discussed for the analysis, including the installing a thermal insulation layer, using external shadings and interior curtains, regulating the optimal comfort temperature, using an economizer, regulating the optimal domestic heat water (DHW) temperature, and installing photovoltaic panels. We investigate heating and cooling energies, as well as the total amount of energy saving in different conditions of the building. The results demonstrate that using the presented strategies leads to 67% and 39.3% reductions in electricity and gas consumption, respectively. Also, the carbon dioxide emissions are decreased 50.5% as a result of implementing the proposed methods.