• Energy Research
• 7. Clean energy close
• 12. Responsible consumption close
• 2. Zero hunger close
• CA close
• Applied Energy close

Abstract Based on an extensive dataset containing aggregated hourly energy consumption readings of residents during March 2011 and October 2012 in South Ontario, Canada, this paper estimates the energy consumption of circulating pumps of residential swimming pools (CPRSP) non-intrusively, and quantifies the impact of CPRSP on the power system. The main challenges are that, first, widely used non-intrusive appliance load monitoring (NIALM) methods are not applicable to this work, due to the low sampling rate and the lack of the energy consumption pattern of CPRSP; second, temperature-based building energy disaggregation methods are not suitable for this work, as they highly depend on the accurate base load estimation and predefined parameters. To overcome these issues, in this paper, first it is found that, during the pool season, for homes with and without swimming pools, the ratio between their base loads is approximately equal to the ratio between their temperature-dependent energy consumptions, then a novel weighted difference change-point (WDCP) model has been proposed. The advantages of the WDCP model are that, on one hand, it doesn’t depend on the base load estimation and predefined parameters; on the other hand, it has no requirement on the data sampling rate and the prior information of energy consumption patterns of CPRSP. Based on the WDCP model it is shown that, the average hourly energy consumption of CPRSP is 0.7425 kW, and the minimum and the maximum hourly energy consumptions are 0.5274 kW at 9:00 and 0.9612 kW at 17:00, respectively. At the peak hour 19:00, July 21, 2011, CPRSP contributes 20.36% energy consumption of homes with swimming pools, as well as 8.48% peak load of all neighborhoods. As a result, the peak load could be reduced by 8.48% if all CPRSP are stopped during the peak hour.

Abstract The effects of the operating conditions on the performance of metal hydride hydrogen storage tanks are complicated and need detailed investigations for further optimization. In this study, a mathematical model is developed to understand the effects of the various operating conditions on the hydrogen absorption processes in a LaNi 5 metal hydride tank. The numerical results indicate that the quickest charging process occurs within the first 20 s, and the quickest charging rate and duration are mainly affected by the charging pressure and initial temperature, respectively. The effect of cooling level on this process is insignificant. For both the short-time charging (2 min) and long-time charging, the hydrogen fueling performance is significantly affected by the cooling level (the heat transfer coefficient and surrounding temperature) and charging pressure. In order to ensure sufficiently quick hydrogen charging, the charging pressure needs to be kept enough higher than the equilibrium pressure, and due to the fast heating of the metal hydride, the influence of the initial temperature is less significant than the cooling condition. The general distributions of the absorbed hydrogen fraction and temperature are similar under the different operating conditions.

The thermal performance of a novel solar air collector with metal corrugated packing in the buildings of cold regions is studied in this paper. Mathematical models are developed to investigate the thermal performance of the collector and the results are verified by experiments. The hydraulic analysis is conducted experimentally to study the pressure drops of the air flows in the corrugated packing. Effects of the structural and operating parameters, such as the collector width, height, specific surface area and solar radiation intensity, ambient air temperature, air inlet temperature and velocity are studied to optimize the thermal performance of the collector. Comparisons are conducted among the metal corrugated packing solar air collector, the unglazed transpired solar collector, the glazed transpired solar collector and the packed bed solar collector with iron chips. The results indicate that the metal corrugated packing solar air collector is more appropriate to be used in the rural buildings of cold regions for its advantages of large heat transfer area, high heat transfer coefficient and good economic performance.

Abstract The objective of this study is to investigate the application of high voltage DC waveforms as a mechanism of load control for convective boiling systems. Electrohydrodynamics (EHD) induces flow pattern redistribution, which directly influences the system performance. EHD can provide a low power (

Abstract Energy storage and transportation technologies play an important role in space exploration missions. Regenerative fuel cells are among the most promising sustainable energy power sources. Compared to secondary batteries, regenerative fuel cells possess unique advantages, including high power density, high specific energy density, light-weight, low-cost, high-efficiency, long-life, and zero environmental impact. More importantly, an regenerative fuel cell is an electrochemical device that can collect and store solar energy during the daytime and release it gradually whenever is needed, making energy available 24/7. Therefore, the development of high-performance regenerative fuel cells in the aerospace sector is becoming more and more important. Herein, in this review, various types of fuel cells are briefly introduced, followed by a detailed discussion and comparison between different unitized regenerative fuel cells. Electrocatalysts and membranes are two of the essential components in the unitized regenerative fuel cells that play a key role in enhancing the system's efficiency. Thus, recent progress and challenges on bifunctional hydrogen and oxygen electrodes are systematically summarized and discussed, respectively. More importantly, the progress and challenges of proton and anion electrolyte membranes are discussed. Further, power performance and durability are two important measures for the application of regenerative fuel cells in space energy systems. Therefore, the current progress of fuel cells in power performance and durability are summarized and discussed. In the end, the key issues and future perspectives of unitized regenerative fuel cells toward space energy storage and transportation are presented.

Abstract Benchmarking energy-efficiency is an important tool to promote the efficient use of energy in commercial buildings. Benchmarking models are mostly constructed in a simple benchmark table (percentile table) of energy use, which is normalized with floor area and temperature. This paper describes a benchmarking process for energy efficiency by means of multiple regression analysis, where the relationship between energy-use intensities (EUIs) and the explanatory factors (e.g., operating hours) is developed. Using the resulting regression model, these EUIs are then normalized by removing the effect of deviance in the significant explanatory factors. The empirical cumulative distribution of the normalized EUI gives a benchmark table (or percentile table of EUI) for benchmarking an observed EUI. The advantage of this approach is that the benchmark table represents a normalized distribution of EUI, taking into account all the significant explanatory factors that affect energy consumption. An application to supermarkets is presented to illustrate the development and the use of the benchmarking method.

Abstract This paper investigates the development and assessment of a model-based predictive control strategy for the district heating system at the Drake Landing Solar Community (DLSC), in Okotoks (Alberta, Canada). Thermal energy is collected by solar thermal collectors and stored seasonally by means of a borehole field. Two water tanks are used as short-term storage, acting as a central unit connecting solar collectors, long-term storage and a district loop. The DLSC has succeeded in using solar energy collected during the summer to provide nearly all the heating needs of this 52-home community in winter, with solar fractions consistently over 90%. The proposed predictive control strategy aims to minimize primary energy consumption while maintaining the same solar fraction. This simulation study –based on model calibrated with on-site measurements– focuses on the optimization of circulation pump speed to manage energy exchange between long-term and short-term storage systems. Minimizing pumping electricity use is a critical aspect of the community environmental impact, since fossil-fuel thermal plants are prevailing in Alberta. Simulation results indicate that the proposed strategy would save, on an annual basis, about 47% of total pump electricity use. This would result in savings in terms of cost (38%) and greenhouse gas emissions (32%).

Abstract This study investigates the performance of a low-operating pressure evaporator using capillary-assisted tubes for adsorption cooling systems (ACS). When using water as a refrigerant in an ACS, the operating pressure is low (

Battery Energy Storage Systems (BESS) are important for applications related to both microgrids and electric vehicles. If BESS are used as the main energy source, then it is required to include adequate procedures for the estimation of critical variables such as the State of Charge (SoC) and the State of Health (SoH) in the design of Battery Management Systems (BMS). Furthermore, in applications where batteries are exposed to high charge and discharge rates it is also desirable to estimate the State of Maximum Power Available (SoMPA). In this regard, this paper presents a novel approach to the estimation of SoMPA in Lithium-Ion batteries. This method formulates an optimisation problem for the battery power based on a non-linear dynamic model, where the resulting solutions are functions of the SoC. In the battery model, the polarisation resistance is modelled using fuzzy rules that are function of both SoC and the discharge (charge) current. Particle filtering algorithms are used as an online estimation technique, mainly because these algorithms allow approximating the probability density functions of the SoC and SoMPA even in the case of non-Gaussian sources of uncertainty. The proposed method for SoMPA estimation is validated using the experimental data obtained from an experimental setup designed for charging and discharging the Lithium-Ion batteries.