Energy Factor Research Articles

An Installed Hybrid Direct Expansion Solar Assisted Heat Pump Water Heater to Monitor and Modeled the Energy Factor of a University Students’ Accommodation

This paper focused on the performance monitoring and modeling of a 6.0 kW, 2000 L hybrid direct expansion solar assisted heat pump (DX-SAHP) water heater used for the production of hot water in a university students’ accommodation with 123 females. The data of total electrical energy consumed, volume of hot water consumed, ambient temperature, relative humidity, and solar irradiance were obtained from the data acquisition systems and analyzed in conjunction with the energy factor (EF) of the system. A multiple linear regression model was developed to predict the EF. The EF of the hybrid DX-SAHP water heater was determined from the summation of the coefficient of performance (COP) of the heat pump unit and the solar fraction (SF) of the solar collectors. The operations of the hybrid energy system were analyzed based on three phases (first phase from 00:00–08:00, second phase from 08:30–18:30, and third phase from 19:00–23:30) over 24 h for the entire monitoring period. The average EF of the hybrid energy system per day during the second phase of operation was 4.38, while the SF and COP were 0.697 and 3.683, respectively. The developed multiple linear regression model for the hybrid DX-SAHP water heater accurately predicted the determined EF.

METHODS OF ENDURANCE DEVELOPMENT GIRLS 16–17 YEARS OLD

The article deals with the modern problem of developing the endurance of girls aged16–17 years by means of fitness, the feasibility of using fitness as a modern type of physical activity.Endurance is one of the most important physical qualities needed in the rapidly changing realities ofmodern life-in physical and psychological aspects. Endurance is a multifunctional property of thehuman body and integrates a large number of processes that occur at various levels: from the cellularto the whole organism. The leading role in the manifestation of endurance belongs to the factors ofenergy metabolism and the vegetative systems that provide it, namely, the cardiovascular, respiratory,and Central nervous system. Endurance training has a beneficial effect on a person”s mental stability.It educates moral and volitional qualities, and especially forms patience and the preservation ofpsychological stability to the effects of external factors. In the modern world, these advantagesare especially important, because life activity in conditions of constant stress, the requirementsof accelerated adaptation, reaction, and the influence of external stimuli becomes difficult for aperson, sometimes unbearable and leads to” emotional burnout “and Manager”s syndrome”. Thehealth of the nation and future generations is largely determined by the health of women. Womenare a large and active part of the population of our country, performing both reproductive anda number of important social functions. Their high-quality performance requires a high level ofmental and General physical stability, namely endurance. Fitness is a progressive trend that integratesphysical activity, proper nutrition, adherence to healthy lifestyle, and is also interesting to younggirls as a modern youth direction of physical activity. The age of 16–17 years is part of the sensitiveperiod of girls “endurance development. A comprehensive assessment of the method of endurancedevelopment is based on changes in the level of General, coordination, strength and psychologicalendurance, changes in the indicators of the cardio-respiratory system and the psychological and emotional component. In order to test the working hypothesis, a natural open parallel pedagogicalexperiment was conducted. The method of endurance development based on a combination ofmeans and methods of classical aerobics, power aerobics, functional, jumping-running and recoveryexercises, combined in qualitative and quantitative composition, with a clear pattern of alternatingtypes of fitness classes and regular use of developed sets of exercises created for girls of high schoolage. According to the results of the experiment, it was found that the functional state of the subjectsimproved, and the necessary training and psychological effect was achieved. The presented analysisof the research results proves the effectiveness of the developed methodology for the developmentof endurance.

A 6M digital twin for modeling and simulation in subsurface reservoirs

A 6M digital twin for modeling and simulation in subsurface reservoirs

Performance analysis of a membrane dehumidifier system subject to component characteristics – a numerical model

In this study, a detailed modeling applicable for membrane dehumidifying system is proposed. This system contains a membrane module, 2-stage vacuum pumps, a condenser, and a regulating valve. The proposed model does not need any prior setting of the vacuum level of the permeate side, and the predictive results are in line with the benchmark. It is found that the COP (coefficient of performance) is 55% higher while the EF (energy factor) is almost 150% higher than the conventional one having the same dehumidifying capacity. For inlet with a fixed relative humidity, both COP and EF are increasd gradually when raising the inlet temperature. Yet the COP and EF reaches the peak values of 5.29 and 6.80 kg/kWh, respectively at a dry bulb temperature near 25.6 °C. Once surpassing this threshold temperature, a pronounced flip-over is seen for both COP and EF. The optimal COP can be obtained by simultaneously adjusting volumetric flowrate and condenser size rather than only adjusting each one individually.

A Novel Energy Factorization Approach for the Diffuse-Interface Model with Peng--Robinson Equation of State

The Peng--Robinson equation of state (PR-EoS) has become one of the most extensively applied equations of state in chemical engineering and the petroleum industry due to its excellent accuracy in predicting the thermodynamic properties of a wide variety of materials, especially hydrocarbons. Although great effort has been made to construct efficient numerical methods for the diffuse interface models with PR-EoS, there is still not a linear numerical scheme that can be proved to preserve the original energy dissipation law. In order to pursue such a numerical scheme, we propose a novel energy factorization (EF) approach, which first factorizes an energy function into a product of several factors and then treats the factors using their properties to obtain the semi-implicit linear schemes. We apply the EF approach to deal with the Helmholtz free energy density determined by PR-EoS, and then propose a linear semi-implicit numerical scheme that inherits the original energy dissipation law. Moreover, the proposed scheme is proved to satisfy the maximum principle in both time semidiscrete form and cell-centered finite difference fully discrete form under certain conditions. Numerical results are presented to demonstrate the stability and efficiency of the proposed scheme.

A Novel Forgery Detection Algorithm for Video Foreground Removal

Video processing software is often used to remove specific moving foreground from a video. Existing forgery algorithms for detecting this type of tampering generally suffer from inefficiency and are not effective for the forged videos under complex background. To address these problems, we propose a novel forgery detection algorithm for detecting video foreground removal. The algorithm first calculates the energy factor (EF) of each frame to identify forged frames. An adaptive parameter-based visual background extractor (AVIBE) algorithm is then designed to detect suspected regions from the forged frames determined in the first stage. After eliminating false detection by calculating the difference of EF between suspected regions in the forged frames and the corresponding regions in the authentic frames, the algorithm finally locates the tampering traces. The experimental results show that our proposed algorithm has higher computational efficiency and accuracy as well as better robustness than those of previous algorithms.

A three-dimensional geometric features-based SCA algorithm for compound faults diagnosis

To achieve compound faults diagnosis with single channel signal, a three-dimensional geometric features-based sparse component analysis (TGF-SCA) method is proposed. Intrinsic characteristic-scale decomposition (ICD) is used to decompose the single channel of mixed signal into three channels. Then, the three-dimensional potential function (TPF) is constructed based on the three-dimensional geometric features to estimate matrix. In addition, an energy factor (EF) is introduced to improve the computational efficiency in the process. Ultimately, the minimal l1 norm algorithm is used to obtain the separated signal based on the estimated matrix. Experimental analysis results for roller bearing show that the fault feature frequencies of bearings acquired using the proposed approach are evidently close to the theoretical values. For example, when the rotating speed is 900 rpm, the feature frequency 60.27 Hz is very similar to the theoretical calculation of ball pass frequency of the outer race (BPFO) 60.5 Hz and the feature frequency 74.01 Hz is close to the theoretical calculation of the ball pass frequency of the roller (BPFR) 74.4 Hz. Compared with the ICA method, the SCA method based on Fuzzy C-means algorithm (FCM) and the SCA method based on K-means algorithm, the experimental verification results indicate that the TGF-SCA method can separate the source signal, extract the fault features and realize compound faults diagnosis for roller bearing.

Experimental evaluation and thermodynamic system modeling of thermoelectric heat pump clothes dryer

Electric clothes dryers consume about 6% of US residential electricity consumption. Using a solid-state technology without refrigerant, thermoelectric (TE) heat pump dryers have the potential to be more efficient than units based on electric resistance and less expensive than units based on vapor compression. This paper presents a steady state TE dryer model, and validates the model against results from an experimental prototype. The system model is composed of a TE heat pump element model coupled with a psychrometric dryer sub-model. Experimental results had energy factors (EFs) of up to 2.95 kg of dry cloth per kWh (6.51 lbc/kWh), with a dry time of 159 min. A faster dry time of 96 min was also achieved at an EF of 2.54 kgc/kWh (5.60 lbc/kWh). The model was able to replicate the experimental results within 5% of EF and 5% of dry time values. The results are used to identify important parameters that affect dryer performance, such as relative humidity of air leaving the drum.

A New Distributed Slot Assignment Algorithm for Wireless Sensor Network Under Convergecast Data Traffic

The scarcest resource for most of the wireless sensor networks (WSNs) is energy and one of the major factors inenergy consumption for WSNs is due to communication. Notonly transmission but also reception is the source of energyconsumption. The lore to decrease energy consumption is toturn off radio circuit when it is not needed. This is why TDMA has advantages over contention based methods. Time slot assignment algorithm is an essential part of TDMA based systems. Although centralized time slot assignment protocols are preferred in many WSNs, centralized approach is not scalable. In this paper, a new energy efficient and delay sensitive distributed time slot assignment algorithm (DTSM) is proposed for sensor networks under convergecast traffic pattern. DTSM which is developed as part of the military monitory (MILMON) system introduced in [27], aims to operate with low delay and low energy. Instead of collision based periods, it assigns slots by the help of tiny request slots. While traditional slot assignment algorithms do not allow assigning the same slot within two hop neighbors, because of the hidden node problem, DTSM can assign, if assignment is suitable for convergecast traffic. Simulation results have shown that delay and energy consumption performance of DTSM is superior to FPRP, DRAND, and TRAMA which are the most known distributed slot assignment protocols for WSNs or ad hoc networks. Although DTSM has somewhat long execution time, itsscalability characteristic may provide application specific time durations.

Enhancement of isobutane refrigerator performance by using far-infrared coating

This study evaluated the effect on refrigeration performance and feasibility of a far-infrared coating (FIRC) on the condenser of a small isobutane (R-600a) refrigerator. The evaluation was based on the no-load pull-down and 24-h on-load cycling tests. Far-infrared materials and a water-based coating material were mixed using a two-step synthesis method to obtain the FIRC material. Fourier transform infrared spectrometry established that the optimal far-infrared material was a multiwalled carbon nanotube (MWCNT). The results of the no-load pull-down test revealed that the electricity consumption, freezer temperature, and coefficient of performance (COP) of the R-600a refrigerator with MWCNT-FIRC (S2) were lower than those of the refrigerator without MWCNT-FIRC (S1) by 3.39%, 3.61%, and 2.92%, respectively. The results of the 24-h on-load cycling test showed that S2 had a lower electricity consumption, higher slope of pull-down (SPD), higher compression ratio (CR), higher COP, lower duty ratio (DR), and higher energy factor (EF), changing upon those of S1 by −7.05%, 5.66%, 3.24%, 5.92%, −5.63, and 7.89%, respectively. A MWCNT-FIRC on the condenser of an R-600a refrigerator can enhance refrigeration performance and reduce electricity consumption, resulting in energy saving and carbon reduction.

A QoE-based Joint Bandwidth and Power Allocation Method for Multiple RATs in HetNets

In this letter, we propose an optimal joint bandwidth and power allocation method for heterogeneous wireless networks (HetNets) by maximizing the users’ quality of experience (QoE), which is a widely used subjective metric reflecting the users’ satisfaction of the multimedia service. By taking two factors into consideration simultaneously: Rate Factor (RF) and Energy Factor (EF), we can measure the QoE of end-users effectively. An optimal QoE-driven allocation algorithm is further developed for maximizing the end-users’ QoE utility subject to the constraints of transmit bandwidth, power and data rate. The simulation results demonstrate the theoretical analysis.

Notes on “Small Signal Analysis of Energy Factor and Mathematical Modeling for Power DC–DC Converters”

In paper (IEEE Trans. Power Electron., vol. 22, no. 1, pp. 69-79, Jan. 2007), large signal and small signal transfer function models of dc-dc power converters are obtained using concept of energy factor (EF) and its associated parameters. In sections II-D and II-E of the original paper, authors describe that the two key parameters of the transfer function are independent of conduction duty cycle k. This is not true and the correct small signal analysis is also reported.

Retrofit assessment of refrigerator using hydrocarbon refrigerants

This study used hydrocarbon (HC) refrigerants in a small R134a refrigerator to evaluate the refrigeration performance and feasibility of using these alternative refrigerants by conducting the no-load pull-down test and 24-hour on-load cycling test. The mixed mass ratios of the HC refrigerants, R290 and R600a, were 65% and 35% (HC1), 50% and 50% (HC2), and 0% and 100% (HC3), respectively. The charged ratios were 30%, 40%, 50%, and 60% based on the charged mass of R134a for HC refrigerants. The results of the no-load pull-down test revealed that the optimal charged mass for all the HC refrigerants was 40% of that of R134a. Most of the experimental results of the HC refrigerators obtained using the optimal charged masses showed that freezer temperature and power consumption were higher than those of the R134a refrigerator. Therefore, the capillary tube lengths of R134a, HC1, HC2, and HC3 were recalculated to be 2.77, 5.05, 5.34, and 5.60 m, respectively, and the recalculated capillary tube was used in the 24-hour on-load cycling test. The results of the 24-hour on-load cycling test showed that the freezer temperatures considerably decreased when the HC refrigerants were used, and that all of the HC refrigerants could be used in the R134a refrigerator after changing the capillary tube lengths. All of the HCs refrigerants yielded lower electricity consumption, lower on-time ratios, and higher energy factors (EFs) than R134a did. The EFs of HC1, HC2, and HC3 were 9.1%, 12.2%, and 42.3% higher than that of R134a, respectively. Using a higher proportion of R600a in HC refrigerants can enhance the EFs of refrigerators.

Performance of Heat Pump Water Heater (HPWH) Systems and Their Impacts on Electric Utility Loads

This work involves measurements, analyses, and evaluation of performance of air-source heat pump water heaters (HPWHs), and their impacts on electric utility loads. Two add-on, heat pumps (HPs) rated at 7000 BTU/h (2.051 kW) and 12,000 BTU/h (3.517 kW) were utilized. The HPs were retrofitted to two 50 gal (189.3 l) electric water heaters (EWHs) with their electric heating elements removed. A third standard EWH was used for comparison. The testing setups were fully instrumented for measurements of all pertinent parameters, including inlet and outlet water temperatures, inlet and outlet air temperatures of the HPs, temperature and humidity of the surrounding air, volume of water drawn out of the storage tanks, as well as the electric energy consumptions of the systems. Performance measures evaluated included the coefficient of performance, the energy factor (EF), and the first hour rating (FHR). The HPWH systems gave EFs ranging from 1.8 to 2.5 and corresponding energy savings (and reductions in utility peak loads) ranging from 49.0% to 63.0%, approximately. The values obtained in the summer months were, as expected, somewhat higher than those obtained in the winter ones. The average values of the EFs and energy savings (and reductions in utility peak loads) were about 2.1 and 56.0%, respectively. FHR results were much lower for the HPWHs compared with those for the standard EWH. These results show that HPWHs are much more efficient compared with standard EWHs. While the average value of the EF for the EWH was about 0.92, the HPWHs yielded EFs averaging more than 2.00, resulting in annual energy savings averaging more than 50%. The results also show that HPWHs are effective at reducing utility peak loads, in addition to providing substantial cost savings to consumers.

Small Signal Analysis of Energy Factor and Mathematical Modeling for Power DC–DC Converters

Mathematical modeling for power dc-dc converters is a historical problem accompanying dc-dc conversion technology since the 1940s. The traditional mathematical modeling is not available for complex structure converters since the differential equation order increases very high. We have to search for other ways to establish mathematical modeling for power dc-dc converters. We have defined energy factor (EF) and new mathematical modeling for power dc-dc converters that have attracted much attention in recent years. This paper describes the small signal analysis of EF and mathematical modeling for power dc-dc converters in continuous conduction mode and discontinuous conduction mode. EF and the subsequential parameters can illustrate the unit-step response and interference recovery. This investigation may be helpful for system design and dc-dc converters characteristics. Two dc-dc converters: Buck converter and super-lift Luo-converter as the samples, are analyzed in this paper to demonstrate the applications of EF, pumping energy, stored energy (SE), capacitor/inductor SE ratio, energy losses, time constant tau, and damping time constant taud

Energy factor and mathematical modelling for power DC∕DC converters

The mathematical modelling of power DC/DC converters is a historical problem that has accompanied DC/DC conversion technology since the 1940's. Traditional mathematical modelling is not available for complex structure converters because of the very high-order differential equations involved. The authors propose a new model to cover all power DC/DC converters. The energy stored in power DC/DC converters has been much considered in the past. A DC/DC converter behaves in this way because it has some energy storing components. When the converter changes from one steady state to another, the corresponding stored energy changes. Therefore, there must be a transient process from one steady state to the new steady state. The authors have theoretically defined a new concept, namely energy factor (EF), and researched the relationship between it and mathematical modelling for power DC/DC converters. The EF and its associated parameters illustrate the unit-step response and interference recovery which may be helpful for system design and in anticipating DC/DC converter characteristics. Two DC/DC converters are analysed, the Buck converter and the super-lift Luo converter, to demonstrate the application of EF, pumping energy (PE), stored energy (SE), capacitor/inductor stored energy ratio (CIR), energy losses (EL), time constant τ and damping time constant τd.

The Energy Factor in Induction Heating Systems

SummaryThis work gives answer to an important questian usually asked in induction heating designs: given a coil and a workpiece. which are the optimal: parameters (frequency and coil-workpiece geometry) to heat this system? TO answer this question a new parameter called Energy Factor (EF) is defined in electromagnetic and in circuit terms. This factor indicates the transfer energy efficiency between two systems (Fig I), in the case of an induction heating system, between the coil and Me load.