Electrical Energy Savings Research Articles

Experimental characterization of an innovative hybrid thermal-electric chiller for industrial cooling and refrigeration application

The energy demand of industries accounts for about 30–35% of world yearly energy consumption, a relevant percentage is due to the need of heating and cooling demand. Solar heating and cooling technologies can be integrated in industrial processes to reduce the fossil fuels consumption as well as the related greenhouse gas emissions. This paper reports the experimental analysis of a novel hybrid sorption-compression chiller for cooling and refrigeration purposes in cascade layout, which uses silica gel/water for the sorption cycle and a low Global Warming Potential (GWP) refrigerant, i.e. propylene for the compression cycle. The experimental results highlighted the flexibility of the system in terms of performances and operating conditions, these were compared to the theoretical performances and it was found out that electricity energy savings from 15% to 25% can be achieved when using the hybrid system over a compression one with the same cooling capacity. The results were converted in performance maps and processed in a statistical model, in order to get a simplified expression for determining the overall performances of the hybrid system through variables that could be measured by a final user, such as the operating temperatures. Optimization strategies were identified for a further enhancement of the performance of the chiller, i.e. the reduction of the electricity consumption, by controlling the intermediate temperature (evaporation temperature of the sorption chiller) through sorption cycle management and the use of variable speed of the pumps in all the circuits to reduce the parasitic consumption especially at low part loads.

Internet of things and cloud computing‐based energy management system for demand side management in smart grid

A smart grid is an electricity network, which deals with electronic power conditioning and control of production, transmission, and distribution of electrical power by employing digital communication technologies to monitor and manage local changes in electricity usage. In the traditional power grid, energy consumers remain oblivious to their power consumption patterns, resulting in wasted energy as well as money. This issue is severely pronounced in the developing countries where there is a huge gap between demand and supply, resulting in frequent power outages and load-shedding. For electrical energy savings, the smart grid employs demand side management (DSM), which refers to adaptation in consumer's demand for energy through various approaches such as financial incentives and awareness. The DSM in future smart grid must exploit automated energy management systems (EMS) built upon the state-of-the-art technologies such as the internet of things (IoT) and cloud and/or fog computing. In this paper, we present the architecture framework, design, and implementation of an IoT and cloud computing-based EMS, which generates load profile of consumer to be accessed remotely by utility company or by the consumer. The consumers' load profiles enable utility companies to regulate and disseminate their incentives and incite the consumers to adapt their energy consumption. Our designed EMS is implemented on a Project Circuit Board (PCB) to be easily installed at the consumer premises where it performs the following tasks: (a) monitors energy consumption of electrical appliances by means of our designed current and voltage sensors, (b) uploads sensed data to Google Firebase cloud over many-to-many IoT communication protocol Message Queuing Telemetry Transport (MQTT) where consumer's load profile is generated, which can be accessed via a web portal. These load profiles serve as input for implementing the various DSM approaches. Our results demonstrate generated load profiles of consumer load in terms of current, voltage, energy, and power accessible via a web portal.

Local Area Positioning System (LAPS) for Indoor Navigation and Tracking System and Building Electricity Energy Saving

Local Area Positioning System (LAPS) for Indoor Navigation and Tracking System and Building Electricity Energy Saving

Influence of Energy-Saving Systems Using Natural Cold on the Energy Intensity of the Milk Cooling Process

Reduction of energy consumption in technological processes of cooling and storage milk on farms is urgent task.(Research purpose) The research purpose is in reducing the energy intensity of the milk cooling process on farms while maintaining its quality.(Materials and methods) The authors conducted research to improve existing and create new smart combined cooling systems based on the rational use of natural and artificial cold sources with means of its accumulation and environmentally friendly coolants with low freezing point.(Results and discussion) The authors have found the dependence of the amount of energy that can be used for cooling and storage of milk and dispersed into the environment on the potential of natural cold of the area and the location of the technological object. The article presents a methodology for assessing the potential of natural cold for different regions of Russia. According to the methodology, authors calculated the values of the ice storage capacities for dairy farms with different livestock and annual milk yield. The article presents the diagram of electric energy savings when using natural cold to cooling milk on farms of 400 heads with a yield of 5000 liters in different climatic regions of Russia. Significant energy savings can be obtained through the use of combined accumulators of natural and artificial cold using environmentally friendly coolants with low freezing point and ground ice storage, in which the freezing of soil and water is carried out due to the ground cooling thermal installation with twophase thermosyphons.(Conclusions) The use of smart combined milk cooling systems on farms on the basis of sources of natural and artificial cold with means of its accumulation and environmentally friendly coolants with low freezing point allows to reduce energy consumption in 1.5-3 times at preservation of its quality. At the same time, such systems in various configurations can be effectively used in all agroclimatic regions of the country.

Energy use optimization in ventilation of operating rooms during inactivity periods

ABSTRACT Hospitals are highly energy-demanding buildings, where simple actuations can involve large savings. However, energy efficiency actions must comply with the high safety standards. Operating rooms demand continuous ventilation despite the short activity periods. Setback during non-occupation of the operating rooms can reduce ventilation loads but must not hinder indoor overpressure to avoid infiltrations. Besides, it prevents any existing heat recovery system from operation. This work evaluates setback ventilation in operating rooms at a case study in Spain, from two approaches: its effect on indoor overpressure and its preference to an existing coil heat recovery (runaround) loop. It based on monitored data of two operating rooms under setback and normal ventilation with operation of the heat recovery system. Seven tests are performed throughout the year, whose comparison to estimated results enables extrapolation to yearly operation. Results show that indoor overpressure maintains at 15 Pa under setback, thus meeting current and coming standards. Setback turned to be always preferable to hear recovery under cooling needs. Estimated heating and electric yearly supply energy savings reach 29 MWht and 262 MWhe, the latter accounting for 2% of the total electric energy consumption of the hospital during 2019.

Localized Property Design and Gradient Processing of a Hydraulic Valve Body Using Selective Laser Melting

Selective laser melting is able to produce complicated functional components. However, it may not simultaneously fulfill the diverse requirements of different parts of a component using uniform process parameters. Gradient processing based on the process parameters is proposed to realize the localized property design. An industrial valve body in a typical hydraulic valve was presented as a case study to demonstrate this concept. Lightweight design was first executed. Then, an experimental study was performed to investigate the influence of the laser power and exposure time on several properties, including the density, hardness, tensile strength, and tribological performance. Based on the specific property requirements of the shell, the fluid passages, and the contact surfaces of the valve body and electrical energy savings of the SLM process, three sets of process parameters were then selected to correspondingly fabricate different parts of the valve body. Results showed that the optimized valve body satisfied the relative density requirement of the shell as well as the yield strength and hardness requirements of the fluid passage. Moreover, compared with a solid valve body fabricated using a single set of default process parameters, the gradient processing leads to reductions from 3.5% to 51.8% in coefficients of friction in different working conditions, and a 4.8% reduction in the electric energy consumption. The lightweight design also contributes to a 21.8% reduction in the weight and a 22.9% reduction in the electric energy consumption. The optimized hydraulic valve also had functional characteristics that were comparable with those for the corresponding conventionally processed valve. This gradient processing was supported by design for property, a valuable technique for integrated design and manufacturing of functional gradient components.

Assessment and optimization of solar absorption-subcooled compression hybrid cooling system for cold storage

The solar absorption-subcooled compression hybrid cooling system is an economically viable energy-saving solution for cold storage refrigeration system. However, the thermodynamic and economic performance of this system has not been assessed specifically for cold storage. Additionally, the system performance strongly depends on the appropriate design of critical parameters, which has not been previously analyzed either. Therefore, a technical and financial evaluation of the solar absorption-subcooled compression hybrid cooling system for cold storage is implemented systematically in this study based on the simulation of the typical days. The effects of the absorption subsystem size and storage tank volume are analyzed. Furthermore, global optimization is performed using the genetic algorithm. It is determined the optimal design is as follows an absorption subsystem size of 0.04–0.06 kW/m2 with a storage tank volume of 40–60 L/m2 for the case in which the collector area (2000 m2) is half the available area. The peak annual electric energy savings is 68.8 kWh/m2. The solar absorption-subcooled compression hybrid cooling system is economically viable for cold storage without any subsidy and the minimum payback period is 4.96 y. This study can be beneficial for the effective and feasible reduction of the energy consumption of cold storage refrigeration systems.

Solar chimney combined with earth to-air heat exchanger for passive cooling of residential buildings in hot areas

In this study, a novel interrelationship between the ventilation rate and the solar chimney design parameters, EAHE geometrical specifications, pressure drop, and climatic conditions in the hot arid area was presented based on experimental and numerical comprehensive investigations. This new correlation simplified designing and optimizing of the passive cooling/heating and ventilation system. Moreover, this correlation was used in a case study of passive cooling/heating and ventilation of a two-stories residential building in Egypt by TRNSYS simulation. The indoor operative air temperatures, heating and cooling loads, thermal comfort conditions, energy consumptions/savings, and CO2 emission savings were calculated and analyzed. Two cases were simulated and compared with the basic-case. In case 1, the basic-case combined with the solar chimney and EAHE. Case 2 had a hybrid passive and active ventilation, which included case 1 equipped with electrical fans that continued operating for 24 h. Finally, an economic study was conducted to calculate the payback period and discount payback period for the construction of such a system using the local Egyptian market equipment. The basic case results show that the zonal temperature was more than the ambient temperature yearly, and in summer, the indoor temperature exceeded the surrounding temperature by 5–6 °C. Using the proposed system in case 1 and case 2 attained a zonal temperature around 5 °C and 9 °C less than the ambient temperature in the summer season, respectively. However, the total annual electrical energy and CO2 emission savings were 42.9 kWh/m2/year and 4.545 tons/year, respectively, in case 2. Finally, the simple payback period was 5.4 years, and the discount payback period was 6.8 years.

Discussion on the Application of New Photovoltaic Energy in Building Electrical Energy Saving

<p>With the rapid development of social economy, the demand for new energy is also increasing, and then the problem of large consumption also has a negative impact on the development of the construction industry. Under the concept of green building, the design and construction units pay more attention to energy conservation and environmental protection, so they actively use photovoltaic new energy in the field of electrical energy conservation of construction projects, so as to improve people's quality of life. Starting from the principles and characteristics of building electrical energy conservation, this paper discusses the methods of building electrical energy conservation, and analyzes how to use photovoltaic new energy in the field of building electrical energy conservation, hoping to better practice the concept of energy conservation.</p>

Analysis on Development and Application of Computer-based Electric Energy Saving Technology and New Power Energy

In recent years, the rapid development of China’s social economy has significantly improved people’s living standards, but it has also led to the increasing demand for electricity in the whole society.This situation has had a very negative impact on the steady development of the social economy.Therefore, it is imperative to strengthen the application of energy saving technology and new energy.At the same time, the increasingly mature computer technology has also given us more ideas in strengthening the energy conservation technology and the application of new energy.The purpose of this paper is to study how to strengthen the application of electricity energy saving technology and new energy in real life by combining computer technology with electricity energy saving technology.

Integrating H2 generation with sewage disposal by an efficient anti-poisoning bifunctional electrocatalyst

Replacing the bootless and sluggish oxygen evolution reaction with the oxidation of some more readily oxidized chemical products is a feasible strategy for energy-saving H2 generation. However, its broad application is inhibited by the costly raw materials, noble-metal catalysts and the toxic effect of organic molecules on catalysts. Herein, we report a novel anti-poisoning MP-MOx (M = Ni, Fe and Mo) bifunctional catalyst that can combine the energy-saving H2 production with sewage disposal simultaneously by directly electrolyzing the wastewater containing organic molecules. The MP-MOx catalyst expresses a commendable electrocatalytic activity for hydrogen evolution reaction and electrooxidation decomposition of small organic molecules (EDM), as well as a remarkable anti-toxicity for organic molecules and a long-term durability. As compared with traditional water electrolysis, the organic electrolytic system exhibits an excellent cell efficient with a cell voltage reducing of 120 mV and can dramatically allow electrical energy savings up to 8% at 10 mA cm−2.

High Performance Oxygen Depolarized Cathodes for Chlor-Alkali Electrolysis Using Electrospun Poly(vinylidene fluoride) (PVDF) Barrier Layers

The industrial production of chlorine via chlor-alkali electrolysis has a significant share of the global energy demand. Significant savings in electrical energy are achieved by using oxygen-depolarized cathodes (ODCs) at the cathode side of the electrolyzer to replace the thermodynamically unfavorable hydrogen evolution reaction. In this manner, the overall cell potential can be lowered by ~1V at industrially relevant conditions (80-90 °C, 30 % NaOH electrolyte). Conventionally used ODCs are porous gas diffusion electrodes consisting of a micro sized silver powder as catalytically active material and polytetrafluoroethylene as hydrophobic binder. With this study, we present a novel and cost effective strategy based on the electrospinning technique to improve the efficiency of commercial ODCs. We demonstrate that implementing a thin hydrophobic layer of poly (vinylidene fluoride) into the electrode structure during the preparation process significantly enhances the electrode performance. In this manner, we are able to reduce the overpotential at industrially relevant current densities of 4 kA m-² by 70 mV. Electrochemical characterization is performed by using linear-sweep-voltammetry (LSV) and electrochemical impedance spectroscopy (EIS) followed by distribution of relaxation times (DRT) analysis. It is proposed that the enhanced electrode performance is mainly caused by an increase in the electrochemically active surface area kept accessible by the hydrophobic layer during operation. Figure 1

A daylight-linked shading strategy for automated blinds based on model-based control and Radial Basis Function (RBF) optimization

Addressing both daylight maximization and glare control over the entire workplace is always challenging for developing the automated shading control system. For the sake of cost and space usage, it is impractical to mount multiple sensors or cameras for real-time daylight environment monitoring to guarantee the control precision. Cut-off control is popular while it cannot attenuate the glare caused by excessive diffuse daylight. This paper introduces a model-based shading control for predetermining shading positions at each time step. A Useful Daylight Illuminance paradigm modality called rUDI is proposed as a variable criterion added to assist the cut-off strategy for further eliminating glare. The controller could be developed through real-time daylight simulations and an optimizer based on the surrogate model. This method was implemented in a full-scale office in Harbin, China. The surrogate model grounded on the Radial Basis Function Neural Network (RBF) was trained, validated and test with the experimental data sets. The control strategy was further incorporated with an adaptive light-switch model. The comparative simulations were conducted, and their corresponding results were generated for evaluating their performance in visual comfort, daylighting and electrical energy savings, demonstrating the advantages of the proposed control approach in terms of its adequate performance.

Energy Efficiency Improvement Considerations at the Design Stage: The Case of Supermarkets

Supermarkets are large energy consumers, with high specific energy consumption than a majority of other commercial buildings. The main energy users are space cooling, lighting and the cold chain. This study was conducted as an initiative to demonstrate cost-effective, replicable ways to achieve significant electrical energy savings in supermarket buildings. The largest consumer of a Supermarket is the HV AC system, with about 50% of the total energy consumption. Of the total demand, the cold chain accounts for about 20% and lighting for about 15% while other equipment use about 15%. The Arpico Super Center, Kegalle, project was selected as a model maximise energy efficiency measures to save electricity. A saving of 22% of energy was achieved through efficiency improvements and a further 23% was self­generated from a roof mount solar power plant. An inverter type air conditioning system, automated fresh air control system with CO2 monitoring sensors, LED lamps, lighting controls (timer switch, light sensor, occupancy sensor), parabolic reflectors, skylights, variable frequency drives (VFD), power factor correction, energy efficient sewerage treatment plant, maximum use of gravity in water transportation and planned preventive maintenance are some of the energy efficiency improvement techniques implemented to achieve the study objectives. Almost all of the Arpico supercenter roofs are operating as solar power plants and more than 3 MWp installations completed by 2019, including 260 kWp of this project.

Analysis of electricity energy savings with Grid-Tie system connected to utility grid

The microgrid consists of at least one energy source that is connected to a load in a relatively small area. In practice, microgrid are divided into two types, off-grid systems or often said to be standalone systems and on-grid systems that are connected to utility networks. The use of renewable energy sources, such as photovoltaic, has become an alternative energy for the problem of electricity energy deficits. This research examines the possibility of saving power consumption from the network using a grid-tie inverter (GTI) power converter in a microgrid configuration so synchronization can be made between renewable energy systems and utility networks. The integration of photovoltaic energy resources with the grid system will increase the value of electricity capacity while reducing the use of fossil fuels, as well as a positive impact where the use of renewable energy can reduce energy use and bills to be paid. Integration of grid tie testing carried out without a load can convert the power generated by almost 90% distributed in the utility network, while testing with a load using a grid tie system, can save power up to 70% of the energy supplied by the utility network.

Research on New Intelligent Building Electrical Energy Saving Technology Based on Internet of Things Technology

In order to continuous the advancement of technology, the development of Internet of Things technology will greatly promote the intelligent, we make information and automation of buildings, which is of great significance for promoting intelligent buildings. The modern intelligent building electrical energy-saving design measures can not only realize the energy-saving design, the real purpose is to save energy and reduce emissions, promote energy-saving emission reduction can promote China’s sustainable development, implement scientific methods, and assist China’s economic development. When designing, we designers should consider various factors and rationally design electrical energy-saving measures.

Improvement of Oxygen‐Depolarized Cathodes in Highly Alkaline Media by Electrospinning of Poly(vinylidene fluoride) Barrier Layers

AbstractOxygen‐depolarized cathodes (ODC) were developed for chlor‐alkali electrolysis to replace the hydrogen evolution reaction (HER) by the oxygen reduction reaction (ORR) providing electrical energy savings up to 30 % under industrially relevant conditions. These electrodes consist of micro sized silver grains and polytetrafluoroethylene, forming a homogeneous electrode structure. In this work, we report on the modification of ODCs by implementing an electrospun layer of hydrophobic poly(vinylidene fluoride) (PVDF) into the ODC structure, leading to a significantly enhanced ORR performance. The modified electrodes are physically characterized by liquid flow porometry, contact angle measurements and scanning electron microscopy. Electrochemical characterization is performed by linear sweep voltammetry and chronopotentiometry. The overpotential for ORR at application near conditions could be reduced by up to 75 mV at 4 kA m−2 and 135 mV at a higher current density of 9.5 kA m−2. Consequently, we propose that modifying ODCs by electrospinning is an effective and cost‐efficient way to further reduce the energy demand of the ORR in highly alkaline media.

Electric Energy Saving of Air-Conditioner for High-Rise Buildings

The application of energy resources has stimulated a dramatic increased especially in developing countries. Consequently, the energy-saving factor of local and non-domestic residents such as the industry, service centers and others has been a concern especially on electronic device equipment such as environmental warming, local ventilation and air conditioning equipment. The method of reducing the use of air conditioners is divided into two methods practiced by engineers is called an active and passive way that alters the model of air conditioning and green building materials. Therefore, this research is intended to reduce the air conditioner energy consumption by avoiding the unnecessary space cooling and stabilize the cooling air at usage area in the high-rise building such as big and tall ceiling hall. Experiment with prototype is chosen to use as the methodology to testing and evaluate the concept according to the change of temperature. Thus, the expected outcomes of experiment are the difference of temperature between upper and lower level will be more significant and lower part is cooler than upper part as the cooling air is avoiding to flowing up by air preventer. Besides that, the air preventer which replace with car tinted able to reflect heat will reduce the heat transfer to the lower part or usage area to reduce the internal heat addition in the high-rise constructing that also benefits to decrease the energy depletion. However, the limitation of air preventer is transmittance of light, costly if apply high quality and bigger space area, and thin layer that may easily broke. The suggested materials that may take in consideration to replace the tinted using Thermoplastic Elastomer (TPE) rubber.

Desiccant cooling as an alternative to traditional air conditioners in green cooling technology

Desiccant-based dehumidification and air conditioning systems are considered as an energy efficient alternative to traditional vapor compression based air-conditioning systems for green building cooling technology especially in tropical hot and humid ambient climates. It is a novel green cooling technology that makes use of low-grade heat for building air conditioning. It is seen that the desiccant based dehumidification and cooling can efficiently provide comfort conditions in subtropical and especially hot and humid tropical climates. The desiccant integrated novel cooling system has a significant higher coefficient of performance compared to the conventional vapor compression system resulting to substantial electrical energy savings during the summer season by use of renewable solar energy, which also resulted in to major reduction in CO2 emissions. Therefore, these results demonstrate that there is a good potential in desiccant-based dehumidification and cooling system for energy and carbon savings while carry out building air-conditioning. Through a literature review, the feasibility of the desiccant assisted air conditioning in hot and humid climatic conditions is proven and the advantages it can offer in terms energy and cost savings are underscored. Keywords: Air-conditioning; Desiccant cooling; Dehumidification; Green cooling; Thermal comfort

A Photo‐Assisted Chargeable Aqueous Zinc‐Iodine Battery

AbstractSolar energy is an abundant and renewable energy resource, but it must be captured and stored for practical application in view of the intermittency and low‐energy density. The search for an effective solar energy storage system is highly required, yet remains a challenge. In this paper, we design a novel solar energy storage device by integrating a TiO2 photo‐electrode into an aqueous zinc‐iodine battery (ZIB). During charging process under illumination, I− in catholyte is oxidized to I3− by photo‐excited holes from TiO2 photo‐electrode. Meanwhile, the photo‐excited electrons transfer to the anode through the external circuit and reduce the Zn2+ into Zn. Due to the compensation of photo‐voltage, an ultralow charging voltage of 0.56 V is achieved, much lower than the discharging voltage (1.2 V), resulting in 54 % input electric energy savings.