A SURVEY OF DOMESTIC WATER HEATING TECHNOLOGIES

ProceedingsConference: ProceedingsIn South Africa, heating water for domestic use is one of the most energy consuming processes in residential buildings. This process represents up to 60% of the total energy in the residential sector. Using more efficient and improved technologies to heat domestic water can make a positive contribution to the fight against the country’s current energy crisis which has a direct implication on the yearly increase in electricity prices. The purpose of this paper is to conduct a survey, summarize and critically analyze the different technologies used to heat water for domestic purposes. The results of this survey aim to identify gaps in the existing research, especially in the case of South Africa. Several research papers and other academic studies are reviewed and classified based on their focus, contribution and the type of technology to achieve a comfortable thermal level of water for domestic use. The key findings indicate importance of implementing hybrid systems for increased reliability and hot water availability while minimizing operating costs

A Review of Water Heating Technologies: An Application To The South African Context

Published Articleup to 40% of their total energy be allotted to the heating of water. The implementation of energy efficient or renewable energy source technologies, for the main purpose of heating water, may assist in reducing the magnitude of the energy crisis that South Africans are facing daily. This will, in turn, reduce energy consumption and costs, so that the energy price hikes do not affect the consumers as severely as it would otherwise. The purpose of this paper is to provide a survey of the most frequently used domestic water heating technologies. The paper aims to critically analyse and summarize recent advancements made in renewable and non-renewable water heating technologies, particularly in the South African case. These technologies include the electric storage tank water heater, solar water heaters (passive and active circulation), heat pump water heater, geothermal water heating, photovoltaic-thermal water heater, gasfired tankless water heater, biomass water heater and oil-fired water heater. Substantial research works and other academic studies focusing on efficiency improvement, optimal design and control, were consulted and categorized in terms of contributions, focus and respective technologies. The key findings of the review conducted on the various water heating technologies are discussed and organized, based on the advantages, drawbacks, approximate initial investment, average life expectancy and payback period. The results of this survey identify gaps in existing research. The aim is to propose a new perspective on the importance of energy efficient hybrid water heating systems and the cost savings they might offer

Optimal Energy Management and Economic Analysis of a Grid-Connected Hybrid Solar Water Heating System: A Case of Bloemfontein, South Africa

Published ArticleIn this paper, the optimal energy management of a hybrid solar electric water heater is presented. A typical medium density household is considered. Actual historic exogenous data, obtained from a weather station in the considered area is used as input for the established model. The aim is to evaluate the energy and cost saving potential of the system, that may be achieved under timebased pricing, while maintaining a comfortable thermal level of the hot water user. Comparisons between the operation of a thermostatically controlled traditional electric storage tank water heater and the hybrid solar electric water heater, offered an energy saving of 75.8% in the winter and 51.5% during the summer period. A life cycle cost (LCC) analysis is presented, where the project lifetime is taken over 20 years. The LCC analysis of the hybrid system demonstrates a 44% saving in overall cost, as compared to a traditional water heating system. Simulation results conclude that the break-even point for the evaluated system was at R10 870 in 3.3 years, under the evaluated time-based pricing structure

Search for the QCD critical point at SPS energies

Lattice QCD calculations locate the QCD critical point at energies accessible at the CERN Super Proton Synchrotron (SPS). We present average transverse momentum and multiplicity fluctuations, as well as baryon and anti-baryon transverse mass spectra which are expected to be sensitive to effects of the critical point. The future CP search strategy of the NA61/SHINE experiment at the SPS is also discussed.Lattice QCD calculations locate the QCD critical point at energies accessible at the CERN Super Proton Synchrotron (SPS). We present average transverse momentum and multiplicity fluctuations, as well as baryon and anti-baryon transverse mass spectra which are expected to be sensitive to effects of the critical point. The future CP search strategy of the NA61/SHINE experiment at the SPS is also discussed

A simplified control method for a water heating load coupled to a hybrid energy system to improve inverter longevity

In this paper, the temperature characteristics of an inverter is determined through experimental validation. The experiment involves testing under two load scenarios. The first of which considers a low inverter load, which represents a baseload at approximately 18% of the maximum rated power of the inverter. The second includes an energy intensive water heater load, which increases the loading on the inverter to above 85%. The aim of this paper is to ensure that the operating limits with respect to the inverter temperature is maintained to at least 10% below the upper limit of the device. The experimental results indicated that the rate of change of the inverter temperature was 2.988 °C/min when loaded above 85% and −1.277 °C/min after returning to the 18% rated output power level. This indicated that if the inverter is subjected to a high load of above 85% for a certain amount of time and the operating temperature has reached its acceptable maximum limit, roughly twice the amount of time is necessary to cool the components down enough for another high loading event. A basic fuzzy logic control method is proposed to maintain the inverter temperature within acceptable limits to improve overall inverter longevity

Optimal operation of a hybrid multisource energy system considering grid load shedding

On-site grid-connected hybrid renewable energy systems are extensively used in the mitigation of scheduled grid load shedding in commercial buildings. This paper proposes an optimal operation of grid-connected hybrid PV-battery-Diesel generator (DG) energy system under scheduled grid load shedding for a commercial building. A mathematical model for an optimal operation of a grid-connected PV-Battery-DG energy system that has a potential of mitigating the scheduled load shedding is developed and implemented. The impact assessment of scheduled load shedding on commercial consumers is also assessed on the cost saving as compared to the baseline without load shedding. Results showcase the potential of the proposed grid-connected hybrid PV-Battery-DG to mitigate scheduled grid load shedding in commercial buildings. Scheduled grid load shedding impacts differently on commercial consumers depending on the scheduled time of a day