Virtual test bench for the design of control strategies for water heaters

2021 ◽  
pp. 1-36
Author(s):  
André Quintã ◽  
Jonathan Oliveira ◽  
Jorge Ferreira ◽  
Vítor Costa ◽  
Nelson Martins
Keyword(s):  
Test Bench ◽  
Control Strategies ◽  
Heat Pumps ◽  
Open Loop ◽  
Hot Water ◽  
Hardware In The Loop ◽  
Water Heater ◽  
Domestic Water ◽  
Virtual Test ◽  
Water Heaters

Abstract An innovative methodology and a virtual test bench are proposed to support the design of water heaters' control strategies. This platform allows to speed up the development and evaluation of control systems even before the existence of prototypes or real test environments. By simulating the environmental conditions and the state of the different device components, it will be possible to detect and correct possible initial errors in the control system design which can be time consuming and costly due to subsequent modifications to the system or equipment components. The architecture of the proposed system establishes four operating modes, open loop data acquisition, real time simulation, hardware-in-the-loop simulation, and test of the complete real system, the incorporation of these functionalities in the same platform is not reported in the literature for domestic water heaters. The virtual test bench was designed to accommodate different water heaters including, but not limited to, gas, electric and heat pumps, for instantaneous hot water production or including hot water storage. The prototype of the virtual test bench is described emphasizing the hardware-in-the-loop methodologies and embedded control. The particular case study of a tankless gas water heater is presented implementing the different operation modes in the virtual test bench. The water heater models, control strategies, simulation and experimental data are presented and discussed.

scholarly journals Comparison of Transcritical CO2 and Conventional Refrigerant Heat Pump Water Heaters for Domestic Applications

Energies ◽  
2019 ◽  
Vol 12 (3) ◽  
pp. 479
Author(s):  
Ignacio Paniagua ◽  
Ángel Álvaro ◽  
Javier Martín ◽  
Celina Fernández ◽  
Rafael Carlier
Keyword(s):  
Heat Pump ◽  
Thermodynamic Cycle ◽  
Heat Pumps ◽  
Design Tool ◽  
Operating Conditions ◽  
Hot Water ◽  
Coefficient Of Performance ◽  
Ambient Conditions ◽  
Water Heater ◽  
Water Heaters

Although CO 2 as refrigerant is well known for having the lowest global warming potential (GWP), and commercial domestic heat pump water heater systems exist, its long expected wide spread use has not fully unfolded. Indeed, CO 2 poses some technological difficulties with respect to conventional refrigerants, but currently, these difficulties have been largely overcome. Numerous studies show that CO 2 heat pump water heaters can improve the coefficient of performance (COP) of conventional ones in the given conditions. In this study, the performances of transcritical CO 2 and R410A heat pump water heaters were compared for an integrated nearly zero-energy building (NZEB) application. The thermodynamic cycle of two commercial systems were modelled integrating experimental data, and these models were then used to analyse both heat pumps receiving and producing hot water at equal temperatures, operating at the same ambient temperature. Within the range of operation of the system, it is unclear which would achieve the better COP, as it depends critically on the conditions of operation, which in turn depend on the ambient conditions and especially on the actual use of the water. Technology changes on each side of the line of equal performance conditions of operation (EPOC), a useful design tool developed in the study. The transcritical CO 2 is more sensitive to operating conditions, and thus offers greater flexibility to the designer, as it allows improving performance by optimising the global system design.

The Thermal Performance of Residential Electric Water Heaters Subjected to Various Off-Peak Schedules

1996 ◽  
Vol 118 (2) ◽  
pp. 73-80 ◽  
Author(s):  
A. H. Fanney ◽  
B. P. Dougherty
Keyword(s):  
Thermal Efficiency ◽  
Laboratory Tests ◽  
Test Procedure ◽  
Hot Water ◽  
Department Of Energy ◽  
Water Heater ◽  
Domestic Water ◽  
Peak Period ◽  
Water Heaters ◽  
Solar Water Heaters

An increasing number of utilities control the supply of power to residential water heaters as one means of reducing peak electrical demand. Water heaters operated in this manner are referred to as off-peak water heaters. Several utilities are also considering the use of solar domestic water heaters as an additional means of limiting power demand during times of greatest electrical usage. The research described within this paper quantifies the variation in thermal efficiency attributable to subjecting residential electrical water heaters to various off-peak and water removal schedules and, thus, forms a basis of comparison to which the thermal efficiency of solar water heaters or other water heating technologies may be compared. Laboratory tests, where the off-peak period and hot water draw schedule were varied, were conducted on two residential storage water heaters. A computer model of an electric water heater was developed and validated. The laboratory tests and the model were used to quantify the effect that various off-peak and hot water draw schedules have on water heater thermal efficiency. Thermal efficiency was found to vary up to seven percent for water heaters which meet the present minimum efficiency standards as specified within the National Appliance Energy Conservation Act. The energy factor, as measured using the Department of Energy Test Procedure for Water Heaters, is shown to be independent of the off-peak schedule because of a “normalizing” that occurs as part of the calculation procedure.

scholarly journals Optimal schedule and temperature control of stratified water heaters

2021 ◽  
Author(s):  
J.A.A. Engelbrecht ◽  
MJ Ritchie ◽  
MJ Booysen
Keyword(s):  
Optimal Control ◽  
Energy Consumption ◽  
Search Algorithm ◽  
Control Strategies ◽  
Optimal Schedule ◽  
Electrical Energy ◽  
Hot Water ◽  
Energy Usage ◽  
Water Heater ◽  
Water Heaters

Water heating is a major component of domestic electrical energy usage, in some countries contributing to 25% of the residential sector energy consumption. Demand response strategies can reduce the time-of-use costs and overall electrical energy consumption. We present a method to reduce the electrical energy usage itself. Our novel heating schedule control minimises the electric water heater's energy usage without compromising user convenience. We achieve optimal control, while taking into account the natural temperature stratification of the water in the tank, using the A* search algorithm. Since previous research assumes a one-node thermal model, we also assess the effect of excluding stratification. We match three optimal control strategies to a baseline: the standard "always on'" thermostat control. The first two strategies respectively match the temperature and the energy of the hot water supplied by the water heater. The third, a variation on the second, includes a method of preventing the growth of Legionella bacteria. We tested 77 water heaters over four weeks, a week for each season, and all three strategies saved energy. The median savings were 6.3% for temperature-matching, 21.9% for energy-matching and 16.2% for energy-matching with Legionella prevention. Taking stratification into account increased these savings by 1.2%, 5.4% and 5.5% respectively.

Heat Pump Water Heater Control Strategy Optimization for Cold Climates

2015 ◽  
Author(s):  
Jayson Bursill ◽  
Cynthia A. Cruickshank
Keyword(s):  
Heat Pump ◽  
Control Strategy ◽  
Control Strategies ◽  
Thermal Storage ◽  
Hot Water ◽  
Space Heating ◽  
Cold Climates ◽  
Water Heater ◽  
Water Heaters ◽  
Surrounding Space

Commercially available heat pump water heaters (HPWH) have been used successfully in warm humid climates (southern United States), and recently, have been proven effective in replacing electric water heater technology in cooler climates within Canada. Using an air source HPWH unit within a dwelling can yield electrical coefficients of performance that are indicative of significant energy savings, but can also add an additional load to the space heating system. Current control strategies do not attempt to mitigate the heating load added to the surrounding space, and only consider the water temperature in the tank. This is because, to date, the primary application has been in sub-tropical climates where cooling is frequently beneficial. Starting in 2015, the US Department of Energy is mandating that all electric water heaters have an energy factor (unit of heat applied to hot water per unit of energy applied to the system) greater than 2, which makes technologies that utilize electrical coefficients of performance, such as HPWH technology, mandatory. To ease the inevitable transition to heat pump water heaters in lieu of electric water heaters, modified control strategies that highlight using thermal storage to reduce space heating loads must be implemented. This paper presents a study which was conducted to evaluate the performance of a commercially available HPWH with modified controls. The HPWH is first characterized experimentally under a series of different thermal conditions and draw parameters. The test tank contains a 1500 W electric auxiliary heater that provides on demand heat to the top 0.30 m (1 ft) of the tank, and a wraparound heating coil. An air source heat pump, using R-134A as the refrigerant, draws air from, and returns air to the surrounding space and provides heating to the whole tank through the coil. The tank has been tested using Canadian Standards Association draw profiles to characterize performance under different hot water demands. Electricity consumption and thermal flux is measured for each vertical tank section, and various performance metrics are calculated using energy balances. A TRNSYS model is then calibrated to the experimental data to allow for the flexibility of varying multiple parameters over various climates. Using this calibrated TRNSYS model, an optimal control strategy and tank set-points can be determined for use in cold climates. As expected from previous work, there is a decrease in performance of the heat pump when heating the tank to higher temperatures to facilitate thermal storage, but the benefits from taking advantage of shifting electrical demand (of water heating) to space heating demand can outweigh the loss of performance.

scholarly journals Assessment and Modeling of Household-Scale Solar Water Heater Application in Zambia: Technical, Environmental, and Energy Analysis

2021 ◽  
Vol 2021 ◽  
pp. 1-13
Author(s):  
Mehdi Jahangiri ◽  
Esther T. Akinlabi ◽  
Sam M. Sichilalu
Keyword(s):  
Fossil Fuels ◽  
Hot Water ◽  
Climate Data ◽  
Ghg Emission ◽  
Water Heater ◽  
Ghg Mitigation ◽  
Solar Water ◽  
Water Heaters ◽  
Industrial Sectors ◽  
Solar Water Heaters

Solar water heaters (SWHs) are one of the most effective plans for general and easy use of solar energy to supply hot water in domestic and industrial sectors. This paper gives the first-ever attempts to assess the optimal localization of SWHs across 22 major cities in Zambia, as well as determine the possibility of hot water generation and model the greenhouse gas (GHG) emission saving. The climate data used is extracted by using the MeteoSyn software which is modeled in TSOL™. Results show the high potential of GHG emission reduction due to nonconsumption of fossil fuels owing to the deployment of SWHs, and three cities Kabwe, Chipata, and Mbala had the highest GHG mitigation by 1552.97 kg/y, 1394.8 kg/y, and 1321.39 kg/y, respectively. On average, SWHs provide 62.47% of space heating and 96.05% of the sanitary hot water requirement of consumers. The findings have shown the potential for the deployment of SWHs in Zambia. The techno-enviro study in this paper can be used by the policymakers of Zambia and countries with similar climates.

Heat Pumps for Energy Saving of Building Hot Water Supply

2011 ◽  
Vol 347-353 ◽  
pp. 587-590
Author(s):  
Qing Hai Luo ◽  
Zheng Zuo
Keyword(s):  
Energy Efficiency ◽  
Energy Consumption ◽  
Water Supply ◽  
Energy Saving ◽  
Heat Pump ◽  
Heat Pumps ◽  
Hot Water ◽  
Low Energy ◽  
Water Heaters ◽  
Hot Water Supply

This paper analyzes the energy consumption of hot water supply in buildings and the insurmountable shortcoming of low energy efficiency of conventional water heaters, and investigates the progress and problems of developing heat pump water heaters. It is pointed out that developing of heat pump water heaters is one of the efficient approaches to improve the energy efficiency of hot water supply.

A New Performance Estimate Method for Design of Storage-Type Domestic Electrical Water-Heaters Based on the CFD Simulation

2010 ◽  
Vol 129-131 ◽  
pp. 463-466
Author(s):  
Li Li Zhao ◽  
Zhi Jun Zhang ◽  
Shi Wei Zhang
Keyword(s):  
Water Temperature ◽  
Cfd Simulation ◽  
Cold Water ◽  
Discharge Rate ◽  
Water Discharge ◽  
Hot Water ◽  
New Method ◽  
Dynamics Simulation ◽  
Water Heater ◽  
Water Heaters

The 3D physical model of the electrical water heater was built. The water-heater performance was resolved by computer fluid dynamics simulation (CFD). The heater performance is characterized by a new method rather than that the discharge efficiency, extraction efficiency and fraction of heat recoverable. The new method is based on the constant discharge water temperature and rate for end user, 5L/min and 43°C that include the hot water from EWH and cold water from outside EWH. But the water discharge rate from EWH was variable as the water temperature discharge from EWH was variable. Compared with the traditional method, it is more close to the user using reality condition.

Solar Water Heaters: A Review of Systems Research and Design Innovation

Green ◽  
2011 ◽  
Vol 1 (2) ◽  
Author(s):  
Brian Norton
Keyword(s):  
System Development ◽  
Unit Cost ◽  
Hot Water ◽  
Water Heating ◽  
Water Heater ◽  
Solar Water Heating ◽  
Solar Water ◽  
Water Heaters ◽  
Systems Research ◽  
And Performance

AbstractSolar water heating can be considered to be an established mature technology. The achievement of this status is the outcome of over a century of system development that culminated with a flourish of innovation in the last thirty years. Drivers for research and development have been achieving economic viability by devising systems that, for specific applications in particular climate contexts produced more hot water per unit cost. Reductions in both initial capital and installation costs have been achieved as well as in those associated with subsequent operation and maintenance. Research on solar water heating is discussed with the emphasis on overall systems though some key aspects of component development are also outlined. A comprehensive taxonomy is presented of the generic types of solar water heater that have emerged and their features, characteristics and performance are discussed.

The Device of the Automatic Backflow in Solar Water Heater-Temperature Control and Backflow for Pipe of Water Heater

2013 ◽  
Vol 827 ◽  
pp. 99-104
Author(s):  
Bin Li ◽  
Xi Chen ◽  
Xin Hao Li ◽  
Lu Kuan Ma ◽  
Wen Bo Lu ◽  
...  
Keyword(s):  
Water Resources ◽  
Cold Water ◽  
Hot Water ◽  
Water Tank ◽  
Solar Water Heater ◽  
Recycle Water ◽  
Delay Effect ◽  
Water Heater ◽  
Domestic Water ◽  
Solar Water

Now in general use in solar water heater, there is a long pipeline between water heater and tap, we have to empty the stored cold water before we use the hot water; and usually the water cannot meet required temperature due to the heating delay effect, thus the water also should be emptied, which leads to a waste of water resources. In order to solve this water wastage, we propose a device which can help to control the temperature and backflow of the water in water heater. The device accomplishes backflow of cold water automatically under the effect of gravity, and refluxed water will be stored in the recycle-water tank, thus ensuring the result that the water temperature satisfies the requirement. After the recycle-water tank is full, it will trigger the buoy to control the relay switch, then the water pump start to work to force the water into the water heater tank. Thus, realizing the recycling of water. This device can significantly save water resources in domestic water, and it has a broad market prospect.

A Study on the Demonstration Experiment of the Solar Hot Water Heater for Dwellings

2005 ◽  
Vol 297-300 ◽  
pp. 2320-2326
Author(s):  
Dong Jo Yang ◽  
Jae Yeol Kim ◽  
Jae Ho Han
Keyword(s):  
Hot Water ◽  
Monitoring Systems ◽  
Short Term ◽  
Water Heater ◽  
Long Period ◽  
Water Heaters ◽  
Extensive Analysis ◽  
Demonstration Experiment ◽  
Routine Procedures

The main purpose of this investigation was to evaluate the performance of the solar hot water heater for dwellings in a long period of time. In order to evaluate the performance, there were 11 solar hot water heaters located in Gwangju Chosun University examined for their performance in 30 month period as a long term. The specific monitoring systems of each heater were constructed for the demonstrational research and the data base associated to each monitoring systems were assembled for an extensive analysis for variety of data obtained. The demonstrational experiments were conducted through following the routine procedures of 4 specific tests (the replicated drainage test, the daily drain test, the daily agitation test, the short-term test). The performance evaluation was based on the performances in insulating and solar collecting and the experimental routines and the performance experiments had incorporated the consumers’ use and need of the product. The ultimate goals of this investigation were to achieve consumers’ trust on the products and to promote the extensive distributions of the solar hot water heaters. The demonstrational research of this investigation was to evaluate the performance of the solar hot water heater for the residents for a long period of time. This research will be continued extensively.

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