Wind energy is one of the most promising renewable energy resources for power generation, and rapid growth has been seen in its acceptance since 2000. The most acceptable classification for wind ...turbines is by its axis of orientation: Horizontal Axis Wind Turbines (HAWT) and Vertical Axis Wind Turbines (VAWT). HAWTs are used in many countries for medium-to-large scale power projects, and most commercial installations around the globe are solely based on these turbines. On the other hand, HAWTs are not recognized as a viable option to harness the energy of the wind in urban areas, where the wind is less intense, much more chaotic and turbulent. VAWTs are suggested as a better choice for cities and isolated semi-urban areas. Several attributes have been suggested for the large-scale deployment of VAWTs, e.g., good performance under the weak and unstable wind, no noise and safety concerns, and aesthetically sound for integration in urban areas. Significant research has been published on wind turbine technology and resources assessment methodologies, and this review paper is a modest attempt to highlight some of the major developments of VAWTs, with a focus on the integration with urban infrastructure. Several recommendations have been drawn based on the state-of-the-art information on the subject for future studies and acceptance of wind turbines in the urban areas. It was concluded that further research is critical in making VAWTs a viable, dependable, and affordable power generation technology for many low and decentralized power applications.
In this paper, a comprehensive review of the artificial neural network (ANN) based model predictive control (MPC) system design is carried out followed by a case study in which ANN models of a ...residential house located in Ontario, Canada are developed and calibrated with the data measured from site. A new algorithm called best network after multiple iterations (BNMI) is introduced to help in determining the appropriate ANN architecture. The prediction performance of the developed models using BNMI algorithm was significantly better (between 6% and 59% better goodness of fit for various models) when compared to a previous study carried out by the authors which used the default single iteration ANN training algorithm of MATLAB®. The ANN models were further used to design the supervisory MPC for the residential HVAC system. The MPC generated the dynamic temperature set-point profiles of the zone air and buffer tank water which resulted in the operating cost reduction of the equipment without violating the thermal comfort constraints. When compared to the fixed set-point (FSP), MPC was able to save operating cost between 6% and 73% depending on the season.
Summary
This research accounts for the outcome of a major cloud‐based smart dual fuel switching system (SDFSS) project, which is a dual‐fuel integrated hybrid heating, ventilation, and air ...conditioning (HVAC) system in residential homes. The SDFSS was developed to enable optimized, flexible, and cost‐effective switching between the natural gas furnace and electric air source heat pump (ASHP). In order to meet the optimal energy consumption requirements in the house and provide thermal comfort for the residents, various high‐quality sensors and meters were installed to record multiple data points inside and outside the house. The performance of the system was monitored in the long term, which is a common practice in energy monitoring projects. Outdoor temperature data plays the most crucial role in operating HVAC systems and also is a key variable in the decision‐making algorithm of the SDFSS controller. Therefore, this study introduces an innovative and unique approach to obtain the outdoor temperature that could potentially replace high precision sensors with a data‐driven model utilizing weather station data at a time resolution of 2 minutes and 1 hour. In this work, a series of artificial neural network algorithms were developed, optimized, and implemented to predict the outdoor temperature with an average of 0.99 coefficient of correlation (R), 1.011 mean absolute error (MAE), and 1.315 root mean square error (RMSE). It has been demonstrated that the developed ANN is a reliable and powerful tool in predicting outdoor temperature. Thus, the proposed model is strongly suggested to be implemented as an alternative to temperature sensors in hybrid energy systems or similar systems requiring accurate ambient temperature measurements.
The cloud based Smart Dual Fuel Switching System (SDFSS) of residential hybrid HVAC system of air‐source heat pump (ASHP) and natural gas furnace/boiler for simultaneous reduction of energy cost and greenhouse gas emission was introduced.
The developed black‐box Artificial Neural Networks (ANN) are able to predict the local building specific location outdoor temperature and suitable for advanced predictive HVAC control.
The proposed technique may lead to the onsite temperature sensors redundant and/or enhanced remote sensor fault detection capability.
We present a study conducted to obtain optimum tilt angle and orientation of a solar panel for the collection of maximum solar irradiation. The optimum tilt angle and orientation were determined ...using isotropic and anisotropic diffuse sky radiation models (isotropic and anisotropic models). The four isotropic models giving varying optimum tilt angles in the range of 37 to 44°. On the other hand, results of the four anisotropic models were more consistent, with optimum tilt angles ranging between 46–47°. Both types of models indicated that the collector tilt should be changed four times a year to receive more solar radiation. The results also indicate that the solar panel should be installed with orientation west or east of due south with a flatter tilt angle. A 15° change in orientation west or east of due south results in less than 1% reduction of the total solar radiation received. For a given optimum tilt angle, the effect of photovoltaic/thermal (PV/T) orientation west or east of due south on the outlet temperature was determined using a one-dimensional steady state heat transfer model. It was found that there is less than 1.5% decrease in outlet temperature for a PV/T panel oriented up to 15° east or west of due south from March to December. This result indicates that existing roofs with orientations angles up to 15° east or west of due south can be retrofitted with a PV/T system without changing the roof shape.
•Comparison of thermal performance between single and double U-tube BHEs was made.•Numerical model that governs unsteady heat transfer in and outside BHE was applied.•Dynamic simulation was made to ...examine the effect of parameters on BHE performance.•Double U-tube BHE has better performance and lower resistance than single U-tube.•CaCl2 (25%) solution showed better thermal performance than other working fluids.
In the ground coupled heat pump system that delivers space heating and cooling to the buildings, often questions are raised as to which borehole heat exchanger configuration (single or double U-tube) provides higher thermal performance. To answer this question, in this paper, detailed comparative transient heat transfer analysis between single and double U-tube borehole heat exchanger (BHE) with two independent circuits (that can operate with the same or different mass flowrate and inlet fluid temperature) is conducted. Validated numerical heat transfer model was applied to perform the dynamic simulation and analysis. The two borehole heat exchangers are compared from the perspectives of their thermal performance in the heating and cooling mode of operation. Detailed sensitivity analysis of the BHE has also been performed by investigating the impact of the important borehole parameters, thermal properties and working fluids on the thermal performance of the double U-tube BHE. The simulation result revealed that the heat injected and extracted by the double U-tube BHE at steady state is 21.8 (77%) and 10.2 W/m (71.8%) more than that of the single U-tube BHE respectively. The simulation results also indicate that the thermal effectiveness of the single and double U-tube BHE at steady state are 0.24 and 0.31 respectively. The single U-tube BHE showed higher borehole thermal resistance than that of the double U-tube BHE with values of 0.47 and 0.31 m.K/W, respectively. The results of the study also revealed that among the studied working fluids, CaCl2 (25%) solution showed better thermal performance than other anti-freeze solutions with thermal effectiveness of 35.6%. The simulation result of this work is crucial as an input for the optimization studies made to obtain a single set of optimal borehole paramaters and thermal properties that results in the best performance of BHE coupled to ground source heat pump system designed to provide space heating and cooling of buildings.
In the field of residential energy conservation, providing tenants with feedback on their energy use has been demonstrated as an effective intervention with savings ranging from 4 to 12%. However, ...methodological issues of past studies have limited our understanding of how best to design feedback. To overcome these issues, this paper leverages a feedback research platform to articulate the feedback design and usage patterns for two variations of real-time feedback dashboards. The first design utilizes historical and goal relevant information, and the second additionally leverages normative comparisons. To evaluate the designs, a year-long field study and energy conservation program was run in a rental multi-unit residential building (MURB) in Toronto, Canada. A year’s worth of pre-study and post-study data was used to benchmark consumption and analyze savings persistence, respectively, of 24 participants. Results showed a significant effect of the conservation program with a relative year-over-year, weather-normalized savings of approximately 12.8%. Exploratory analyses showed increased engagement with normative comparisons along with intra-day behaviour changes that appeared to persist along with savings a year after feedback was removed.
Due to their significant internal heat gain resulting from computer server banks, data centres require cooling year-round, creating an opportunity to transport the waste heat to heat-deficient ...neighbouring buildings. This paper evaluates the quantity of multi-unit residential buildings (MURBs) that should be connected to a given data centre in order to maximize the portion of shared energy which provides the MURBs’ heating energy and the data centre's cooling energy simultaneously. The paper then evaluates the financial viability and greenhouse gas (GHG) emissions of three different methods with which energy can be shared from a data centre to surrounding MURBs in a community energy network (CEN). The first method, called the Energy Sharing System involves using a heat pump to produce heating and cooling at the same time for the MURBs and the data centre. The second, called the One-Borefield System, has the same energy sharing aspect as the first, with additional heating and cooling coming from geo-exchange. The third method, called the Two-Borefield System, is an innovative approach to geo-exchange, which uses two separate borefields to achieve free cooling, while also incorporating the energy sharing base. The investigation finds that the optimal MURB area that should be connected to a 4000 kW cooling load data centre is 110,000 m2 for the Toronto (Canada) climate. The financial analysis shows that the Energy Sharing System was the most profitable, with a 11.9% 30-year unlevered after-tax internal rate of return (IRR).
Small and medium industries (SMEs) savings analysis can help to reduce energy consumptions and greenhouse gas emissions (GHG) and support the individual company to make a better decision to improve ...facility energy performance. The main idea was to get enough data to recreate simple Excel-based tool so that SMEs could conduct quick energy and GHG emission benchmarking and to come up with potential savings by using their utility bills and plant specifications. Having such knowledge will help these industries to promote energy efficiency, sustainability, and competitiveness in their operation. Energy consumption data of eleven companies have been collected and analyzed. The methodology involves energy benchmarking, separation of process and seasonal energy consumptions, heating degree days estimation, normalized annual energy consumption, and normalized process and seasonal energy consumptions. The leading performance indicator was identified energy intensity of oven. It was estimated, the energy intensity of bake ovens varies from 24 m3/ft3 to 30 m3/ft3, while the energy intensities of ovens with finishing process varies from 8 m3/ft3 to 36 m3/ft3. Potential savings can be realized from retrofits such as the addition of a VFD controller (exhaust loss), insulation (shell loss). Depending on the investment and the type of estimated retrofits, the return on investment can be realized in less than a year or up to ten years. It was also noted that by optimizing production scheduling; 8%–69% of energy consumption could be saved by proper shut-down and scheduling the non-production hours.
Flow diagram of research program to investigate energy-saving opportunities of SMEs in the GTA. Display omitted
•Small and Medium Enterprises energy analysis, performance indicators, and savings potential.•Methodology involves heating degree days, normalized annual process and energy consumptions.•The observed energy intensity of ovens varies from 24 m3/ft3 to 30 m3/ft3 (and 8 m3/ft3 to 36 m3/ft3).•Savings can be realized from retrofits of a VFD controller (exhaust loss), insulation (shell loss).•Natural gas savings from the facilities processing varies from 19% to 53%.
Through tests conducted at the Toronto and Region Conservation Authority’s (TRCA) Archetype Sustainable Houses, a hybrid residential space heating system with a supervisory controller was monitored ...and studied to evaluate its performance and effectiveness for the heating season. A high efficiency natural gas furnace (NGF) and an electric air source heat pump (ASHP) were coupled together to meet the space heating demand of the house. This integrated system is called the cloud based Smart Dual Fuel Switching System (SDFSS) that considers time-of-use (TOU) pricing, fuel cost, short-term weather forecast, and equipment efficiencies and capacities. This multi-variable decision-making process defines an optimal schedule for the hybrid system to run more cost effectively. This paper analyses two separate SDFSSs. According to these analyses, the SDFSS systems showed lower operating cost with respect to the furnace or the ASHP system alone with various carbon tax (CT) levels from $0 to $250/tonne of CT with an increment of $10/tonne of CT that were simulated, along with a significant GHG emission reduction relative to the conventional heating systems. Furthermore, with these technologies, Canada’s residential sector could potentially meet Canada’s Paris Agreement goals. The SDFSS technology is a is flexible, user friendly, ubiquitous technology for the smooth transition from today’s natural gas dominated space heating system to the future’s low carbon infrastructure powered by a heat pump and renewable energy.
•Variation of the stream properties in the syngas-fueled hybrid SOFC–GT cycle.•Detailed analysis of the operation of the methane-fueled SOFC–GT cycle.•Investigate effects of inlet fuel type and ...composition on performance of cycle.•Comparison of system operation when operated with and without anode recirculation.
In this paper, the hybrid solid oxide fuel cell (SOFC) and gas turbine (GT) model was applied to investigate the effects of the inlet fuel type and composition on the performance of the cycle. This type of analysis is vital for the real world utilization of manufactured fuels in the hybrid SOFC–GT system due to the fact that these fuel compositions depends on the type of material that is processed, the fuel production process, and process control parameters. In the first part of this paper, it is shown that the results of a limited number of studies on the utilization of non-conventional fuels have been published in the open literature. However, further studies are required in this area to investigate all aspects of the issue for different configurations and assumptions. Then, the results of the simulation of the syngas-fueled hybrid SOFC–GT cycle are employed to explain the variation of the stream properties throughout the cycle. This analysis can be very helpful in understanding cycle internal working and can provide some interesting insights to the system operation. Then, the detailed information of the operation of the methane-fueled SOFC–GT cycle is presented. For both syngas- and methane-fueled cycles, the operating conditions of the equipment are presented and compared. Moreover, the comparison of the characteristics of the system when it is operated with two different schemes to provide the required steam for the cycle, with anode recirculation and with an external source of water, provides some interesting insights to the system operation. For instance, it was shown that although the physical configuration of the cycle in two systems is the same, the actual configuration (the equipment actually taking part in the process) can be different. Finally, the results of the simulation for different types of the inlet fuel show that system outputs and operational parameters are greatly influenced by changes in the fuel type. Therefore, the possibility of variation of the inlet fuel type should be considered, and its impacts should be investigated before utilization of biogas, gasified biomass, and syngas as fuel in hybrid SOFC–GT cycles.
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