Cumulative Energy Consumption Research Articles

Crack characteristic and fractal analysis of SFRC shear wall with CFST columns under repeated low cycle load

In this study, we conducted a comprehensive analysis of the crack characteristics and fractal behavior in steel fiber reinforced concrete shear walls (SFRCSW) reinforced with concrete-filled steel tube columns (CFSTCs) under repeated low-cycle loading conditions after failure. Notably, the incorporation of steel fibers and CFSTCs did not alter the fundamental shear failure mode but effectively constrained crack widths to 2.0 mm and 1.6 mm, respectively, from an initial width of 2.4 mm. The use of steel fibers or CFSTCs led to significant improvements in the surface crack fractal dimension (SCFD) of shear walls, with increase ratios of 9.7 % and 7.88 %, respectively. Conversely, an increase in SCFD was associated with improvements in yield load, peak load, failure load, and cumulative hysteretic energy consumption in SFRCSWs. SCFD is suitable for comparative evaluation of the bearing capacity and energy dissipation capacity of different shear walls, but it is not suitable for comparative evaluation of displacement and ductility. For shear walls, it seems more reasonable to evaluate the damage degree in loading process by displacement - fractal dimension relation, rather than load - fractal dimension relation, with the critical values of fractal dimension are about 1.12 and 1.17.

The Effect of Energy Management in Heating–Cooling Systems of Electric Vehicles on Charging and Range

In this study, an energy management model for electric vehicles including the entire vehicle such as the cabin, electric motors, battery, and the heating–cooling system was prepared. The heating and cooling processes for electric vehicles were run according to the internationally recognized driving cycles as well as at constant speeds to investigate them under different ambient conditions. The heating–cooling processes were managed in line with the cabin temperature target determined by considering the comfort conditions. The energy consumption of each of the system elements and the system in the heating–cooling process in electric vehicles was analyzed. Under different operating conditions, the variation of cabin temperature with time, instantaneous power, and cumulative energy consumption was calculated. The effect of heating and cooling processes on energy consumption, charging rate, and range were analyzed and interpreted. The results showed that the heating–cooling system for the heating process consumed more energy when the ambient temperature decreased, and the charge consumption ratio as well as the range deformation rate increased to about 30% when the ambient temperature was –10 °C. Similarly, the heating–cooling system for the cooling process consumed more energy when the ambient temperature increased, and the charge consumption ratio as well as the range deformation rate reached up to 40% when the ambient temperature was 40 °C. When the outdoor conditions were close to the thermal comfort temperature of 23 °C inside the cabin, the total energy consumption and the range deformation rates were reduced to less than 10%.

Advancing earthquake resistance: Hybrid retrofitting of RC frames with FRP and TDS

Traditional and technological retrofitting methods have been proposed over time to enhance earthquake resistance in structures. Friction-type dampers have attracted considerable interest from both researchers and the construction industry because of their versatility in retrofitting, quick installation, and non-destructive characteristics. Moreover, the integration of damping systems with various retrofitting elements and the resulting impact of these hybrid systems on building performance have consistently been subjects of interest. This study involved the construction of three identical half-scale reinforced concrete (R.C) frames. One frame served as the reference (REF), the second was wrapped with Fiber Reinforced Polymers (FRP) material (REF-FRP), and the third was retrofitted using both FRP wrapping and the developed Technological Damper System (TDS-FRP). Quasi-static cyclic experiments were performed on the three structural frames, providing force-displacement and force-rotation relationships. The acquired data were then used to assess the damage states of the frames according to the Turkish Building Earthquake Code (TBEC 2018), and energy consumption rates were determined. Moreover, Finite Element Method (FEM) analyses were performed on REF, REF-FRP, and TDS FRP frames to derive force-displacement relationships, which were subsequently compared with experimental findings. The experiment results indicate that the horizontal load-carrying capacity of the TDS-FRP frame increased by 76 % to 122 % compared to the REF frame, while the REF-FRP frame showed a maximum increase of 14 %. Additionally, the cumulative energy consumption capacity of the REF-FRP frame increased by a maximum of 42 % compared to the REF frame, and the TDS-FRP increased between 51 % and 156 %. At a 1 % drift ratio, shear cracks at the beam ends and column-beam intersections of the REF frame were observed to be significantly reduced in the REF-FRP frame and eliminated in the TDS-FRP frame. Additionally, upon reaching a 3 % drift ratio, it was observed that the TDS-FRP frame remained within acceptable limits as per TBEC 2018, whereas the REF and REF-FRP frames exceeded the advanced damage limit. Additionally, it has been observed that the results obtained from FEM analyses coincide with the experimental results. In this context, the TDS-FRP hybrid application can be considered as an effective and alternative solution for the R.C buildings.

The Seismic Performance of Self-Centering Ribbed Floor Flat-Beam Frame Joints

To achieve rapid post-earthquake repair of self-centering ribbed floor flat-beam frame structures, a ductile hybrid joint consisting of dog-bone-shaped, weakened, energy-dissipating steel bars connected to the upper and lower column sections through high-strength threads is proposed based on the damage control design concept. By moving the ductile energy-dissipating zone out to the locally weakened section of the energy-dissipating steel bars and the locally unbonded prestressed steel bars in the core area, the residual deformation was limited and the seismic performance improved. Based on the working principle of hybrid joints, low cycle loading tests were conducted on two joint specimens to analyze the influence of lateral prestress on the seismic performance of the hybrid joints. Numerical modeling methods were used to compare the position of the energy-dissipating steel bars in the composite layer and the friction performance of the joints. The research results indicated that the hybrid joint had stable load bearing, deformation, and energy dissipation capabilities, with damage being primarily concentrated in the energy-dissipating steel bars. Even at an inter-story displacement angle of 5.5%, the upper and lower column segments remained elastic. After unloading, the connection seam at the joint was closed, and the self-centering performance was good. When the inter-story displacement angle reached 5.5%, the lateral prestress increased from 150 kN to 250 kN, the ultimate bearing capacity of the joint increased by 16.3%, and the cumulative energy consumption increased by 30.0%. The influence of the friction coefficient of the joint surface on the structural performance was set at a threshold of 0.7. When it was less than the threshold, the ultimate bearing capacity and initial stiffness of the joint increased with the increase in the friction coefficient. After reaching the threshold, the increase in the ultimate bearing capacity of the joint slowed down, and the rate of stiffness degradation gradually accelerated. This joint showed excellent seismic performance and can thus achieve post-earthquake repair of structures.

Energy consumption optimization model and system for the pellet drying process of straight grate

The drying process is a crucial stage in the thermal treatment of iron ore pellets in a straight grate, as it has a direct impact on pellet quality and energy consumption. Consequently, this paper develops a simulation model for the pellet bed drying process, which is validated through industrial data and enables the visualization of temperature and moisture distribution within the pellet bed. Based on the simulation model, an optimization model for the drying process is developed to minimize the specific energy consumption per tonne of green pellets. The constraints of the drying process are the moisture content requirements and burst temperature. A genetic algorithm is employed to optimize the parameters such as trolley speed, pellet bed thickness, air temperature, and air pressure. The results show that, with an absolute error criterion of 10 °C, the temperature calculation accuracy of the simulation model exceeds 86%, effectively describing the drying process in a straight grate sintering machine. Under yield limitations, the optimal cumulative energy consumption per tonne of green pellet is reduced by 1.50% during the drying process. Finally, a simulation and optimization system for the drying process in the straight grate is implemented in C++. This system not only generates essential data for designing the drying section in a straight grate but also lays a theoretical foundation for system optimization and optimal control.

The behavior of reinforced concrete frames exposed to high temperature under cyclic load effect

Continued use of the structure through minor renovations and repairs without a complete and accurate determination of the extent of damage to the structure and its elements exposed to high temperature effects due to fire, etc. will cause more loss of life and property in the event of an earthquake that may occur later. The aim of this study is to determine the losses on the lateral load and energy damping capacities and stiffness of reinforced concrete frames exposed to 200, 400, 600 and 800 ℃ high temperatures for 60, 120 and 180 min. For this purpose, 13 reinforced concrete frame test elements with the same concrete and steel material properties and dimensions were produced. All reinforced concrete frame test members were brought to the specified target temperature within one hour and exposed to high temperature effects for 60, 120 and 180 min at these target temperatures. The test members then allowed cooling down on their own and when they reached room temperature, they removed from the oven and subjected to cyclic lateral loading tests. The data obtained from the cyclic lateral loading tests processed to obtain lateral load - horizontal displacement, stiffness - horizontal displacement, cumulative energy consumption - horizontal displacement and strength envelope curves for each test element. According to the results of the cyclic lateral loading tests, it was determined that the lateral load carrying capacities of the test members exposed to high temperature for 60, 120 and 180 min decreased by 24 %, 33.33 % and 36 % in push, and by 25.76 %, 37.6 % and 38.72 % in pull, respectively. In addition, the energy consumption of the test elements exposed to high temperature for 60, 120 and 180 min decreased by 30.98 %, 42.41 % and 39.62 %, respectively, compared to the reference test element. The initial stiffness of all test elements exposed to the high temperature effect decreased compared to the initial stiffness of the reference test element not exposed to the high temperature effect. According to these results, the effect of high temperature causes losses in many parameters that are of vital importance in the building elements, but also highly affects the earthquake behavior of the building.

Ultra-low cycle fatigue test study of bolted spherical joints in steel grid structures

During a catastrophic earthquake, bending and failure were exhibited in the bolted spherical joints, and these phenomena have obvious ultra-low cycle fatigue (ULCF) failure characteristics. To study the failure characteristics, hysteresis behavior, stiffness degradation, and energy consumption of bolted spherical joints, the ULCF test of bolted spherical joints specimens was carried out. The experimental study showed that the high-strength bolts experienced an ULCF failure process of bending, crack initiation, crack propagation, and instantaneous failure, and the fatigue life of the specimens was less than 20 times. The pinch phenomenon in the hysteresis curve of the specimen was significant, indicating that its energy consumption was poor. The energy-damage model of the specimens under cyclic displacement was derived based on the cumulative energy consumption. A damage assessment method for the specimen was proposed based on the energy-damage model and angle change characteristics of the specimen. This method provides a reference for damage assessment and repair design of bolted spherical joint grid structures after an earthquake.

Validation of a statistical-dynamic framework for predicting energy consumption: A study on vehicle energy conservation equation

Predictive models for vehicle energy consumption are crucial for sustainable development in urban road traffic systems. This paper comprehensively reviews classic predictive models and develops a novel statistical-dynamical energy consumption prediction framework called Vehicle Energy Conservation Equation (VECE). VECE is constructed based on the principles of vehicle energy flow and regression analysis, employing a continuous and concise mathematical formulation. Its coefficients possess clear physical interpretations, allowing for application in various vehicle categories. To validate VECE, this study collected energy consumption data from 28 vehicles, including 9 diesel vehicles, 16 gasoline vehicles, 1 ethanol gasoline vehicle, and 2 battery electric vehicles. A rigorous data processing procedure was designed. Data analysis revealed that the VECE coefficients are correlated with vehicle type, speed, and acceleration. VECE's predictive performance is minimally impacted by the number of vehicle categories, effectively modeling energy consumption for vehicles of the same fuel type or size category. Comparative analysis with E-EcoGest, VT-Micro, PERE, and CMEM demonstrates the moderate accuracy of VECE in predicting instantaneous vehicle energy consumption while excelling in predicting cumulative energy consumption. The minimum relative percentage error for the cumulative predicted values is 4.2%. Overall, VECE demonstrates outstanding performance in computational simplicity, coefficient interpretability, adaptability, and extensibility, making it a crucial tool for achieving energy-efficient road transport systems.

Seismic performance and flexural strength prediction of high-strength bar reinforced UHPFRC walls under high axial load ratio

A new-type shear wall built with high-strength reinforcement and ultra-high performance fiber reinforced concrete (UHPFRC) is proposed in this paper, aiming to solve the problem of too large cross-section size of bottom shear wall members of high-rise and super high-rise buildings. Four UHPFRC wall specimens built with high-strength reinforcement were tested under cyclic loading to examine the influence of the parameters of fiber volume fractions (0 vs. 1.5% vs. 2.5%) and the spaces of horizontal distribution reinforcing bars (150 mm vs. 300 mm) on the seismic performance. In addition, a calculation method of flexural strength of UHPFRC shear wall is established. The research results show that: the UHPC wall specimen without fibers failed in the axial compression brittle mode, and the UHPFRC wall specimens with fibers failed in flexure-dominated ductile mode. The bridging effect of steel fibers at the cracks kept the integrity of the UHPFRC. The drift ratio capacities of the UHPFRC wall specimens under high axial compression ratio of 0.5 were 3.56%. Increasing the fiber volume fractions can improve the strength, initial stiffness, and cumulative energy consumption of the wall specimens, reduce the damage degree of the UHPFRC at the toes of the wall specimens, and can also reduce the reinforcement ratio of horizontal reinforcement without influence on the seismic performance. The proposed method of flexural strength of UHPFC walls shows reasonable prediction accuracy.

Degradation of Mechanical Performance of Hoop Head Tenon-Mortise Joint of Tusi Manor with Decay Disease in Tibetan Areas in Yunnan

(1) The Hoop Head Tenon-mortise Joint (HHTMJ) in the Tusi Manor in Tibetan areas in Yunnan, China, has a serious decay phenomenon. To understand the effect of decay on the seismic performance of HHTMJ, (2) the five groups of HHTMJ and small-size Pinus kesiya var. langbianensis wood mechanical property testing specimens were placed in an artificially set decay environment and cultivated together with wood decay fungi for 0, 6, 12, 18, and 24 weeks, respectively. Low-cycle repeated loading tests were conducted to compare the failure mode, hysteresis curve, skeleton curve, and cumulative energy consumption of the HHTMJ under different decay cycles. (3) The results indicate that the failure mode of the HHTMJ is fractured at the tenon shoulder, and the deformation and failure of the tenon increase with the increase in decay. Compared with the non-decayed specimens, the ultimate bearing performance of the specimens after 6, 12, 18, and 24 weeks of decay decreased by 8.83%, 16.97%, 19.69%, and 30.22%, respectively. The cumulative energy consumption decreased by 21.6%, 27.4%, 33.2%, and 41.3%, respectively. (4) Decay primarily occurs on the exterior of the tenon, with minimal decay on the interior. The degradation of seismic performance in HHTMJ is relatively close to the degradation observed in small-size wood specimens during mechanical property testing.

Seismic response and failure mechanism of ordinary concrete and UHTCC short columns reinforced with negative Poisson's ratio steel bars

The replacement of ordinary steel bars by negative Poisson's ratio (NPR) steel bars to improve the seismic performance of short columns is investigated in this study. NPR steel bars is a new type of reinforcement with negative Poisson's ratio effect and high strength and ductility. In this paper, six short column members were designed. Among them, P-RC1 and P-UHTCC1 short columns were used as controls, and the remaining four specimens were reinforced by NPR steel bars. The failure mode, cracking pattern, hysteresis characteristics, plastic deformation capacity, shear strength, stiffness degradation and energy dissipation capacity of the specimens were investigated through lateral cyclic loading tests. The experimental results showed that the shear capacity of short concrete columns reinforced with NPR steel bars increased by 20.91%−22.64% and the cumulative energy dissipation capacity increased by 45.7%−63.3%. The short UHTCC columns reinforced with NPR steel bars showed an increase in shear capacity of 23.08%−35.48% and an increase in cumulative energy consumption capacity of 17.3%−28.5%. And the RC columns shear strength prediction model based on GB50010–2010 specification is relatively reasonable to be used for the evaluation of shear strength of short columns reinforced with NPR steel bars.

Assessing the Environmental Impact of Plastic Waste using Life Cycle Assessment

This research use a life cycle assessment (LCA) paradigm to investigate the environmental effects of plastic waste management practices. The environmental impacts of these processes are measured using experimental data. The acquisition of raw materials, particularly in plastic manufacturing, results in considerable environmental consequences, including an energy expenditure of 1200 MJ and the release of 300 kg of CO2. Likewise, waste processing activities, such as plastic shredding and molding, need 1500 MJ of energy and produce 400 kg of CO2 emissions. The operational lifespan of the product is underscored in its usage phase, wherein Plastic Product A and Plastic Component B exhibit cumulative energy consumption of 100 MJ/year and 120 MJ/year, alongside emissions of 20 kg CO2/year and 25 kg CO2/year, respectively, thereby accentuating the significance of a product’s lifecycle. The end-of-life phase underscores the variety in recycling rates, emphasizing the need for more effective recycling techniques. This comprehensive LCA methodology delineates critical areas for improvement, directing sustainable plastic waste management methods and fostering environmentally responsible decision-making within the sector. The results provide a more sustainable method for handling plastic garbage and diminishing its ecological impact.

A hybrid on-line approach for predicting the energy consumption of electric buses based on vehicle dynamics and system identification

Energy consumption modeling for electric vehicles is conducive to achieving eco-driving optimization and alleviating driver ‘range anxiety’. However, it remains challenging due to the complexity of influencing factors. In this study, we propose a novel hybrid cumulative energy consumption (CEC) prediction approach by a combination of vehicle dynamics and the forgetting factor recursive least squares (FFRLS) to achieve real-time online forecasting accurately. The approach is developed with real-world data collected from over 983,000 frames across six electric buses in Guangzhou, China. To enhance the accuracy and practical application of the approach, we divide the data into segments as a unit of calculation for CEC. Subsequently, we constructed the model in three working conditions based on the vehicle longitudinal dynamics, and determined the parameters to be estimated for the model. With the help of the online learning capabilities of FFRLS algorithm, the estimated parameters can be constantly adjusted and updated according to the state of the buses. The results demonstrate that the mean absolute percentage error (MAPE) of the proposed method is 7.05 %. This performance surpasses that of existing relevant studies, indicating that the model provides a more accurate method for eco-driving and city-scale electric bus operation systems.

Research on Nonlinear Behavior of Local High-Performance Concrete Beam-Column Connections.

The seismic performance index of prefabricated structures is generally obtained via experimental analysis. However, in experimental research, it is impossible that every influencing factor can be taken into account. Therefore, the finite element analysis method can be used as a supplementary method for experimental research to carry out parametric analysis of joints. Based on this test, a hysteretic model of steel bars is developed on the ABAQUS platform; meanwhile, the model is used to simulate the seismic analysis of the proposed local reinforced joints. The hysteresis curve obtained via simulation exhibits a high degree of coincidence with the experimental results. Based on the validated model, a detailed parameter analysis of prefabricated local reinforced concrete frame joints is carried out. The analysis results illustrate that the axial pressure ratio at the top of the column has a minimal impact on the joint's performance. Decreasing the stirrup ratio within the core region, enlarging the diameter of the PC steel bar, and increasing the concrete strength that is poured in the keyway and the core region can raise the cumulative energy consumption of the joints, thereby reducing the damage degree of other units and improving the maximum bearing capability of the joints.

Research on the Estimation Model of Energy Consumption Capacity for Reinforced Concrete Components with Axial Force

The research group utilized the estimation model of energy consumption capacity for reinforced concrete components without axial force to assess the energy consumption capacity of 92-reinforced concrete components from the PEER database, which were subjected to axial force and bending. The study also examined the impact of design parameters, including longitudinal reinforcement ratio, transverse reinforcement ratio, axial compression ratio, and shear-span ratio, on the estimation results. The research findings revealed that when applying the estimation model of energy consumption capacity for reinforced concrete components without axial force to calculate the energy consumption capacity of reinforced concrete components with axial force, there was a significant deviation rate in the estimation of cumulative energy consumption. The relationship between the deviation rate of cumulative energy consumption and longitudinal reinforcement ratio, axial compression ratio, and shear-span ratio remained unclear. However, a more apparent linear relationship was observed with the transverse reinforcement ratio. By conducting a quantitative analysis of the transverse reinforcement ratio, the researchers proposed an modified estimation model of energy consumption capacity for reinforced concrete components with axial force. Nonetheless, the accuracy of the modified estimation model was found to be high within the range of 0–250,000 kN mm of cumulative energy consumption. For cumulative energy consumption exceeding 250,000 kN mm, further experimental and theoretical research is still required to enhance the reliability of the modified estimation model.

Experimental and Numerical Study on the Shear Performance of the Stone Panel–Panel Joint in Stone Cladding

The evaluation of the shear performance of stone panel–panel joints (SPPJs) in stone cladding has important engineering significance, as it plays a crucial role in stone cladding failure. The purpose of this paper is to analyze and predict the influence of the dimension and the Young’s modulus of sealant on the shear performance of SPPJs. Based on monotonic and cyclic loading tests, the effects of Young’s modulus and the dimension of sealant on the failure characteristics, stress–strain characteristics, stiffness degradation, and energy dissipation capacity of an SPPJs were investigated. According to finite element analysis, the strain distribution of an SPPJ under monotonic loading was analyzed for different sealant widths and number of sealant layers. The results indicate that the failure modes of SPPJs change with the variation of sealant amount. As the Young’s modulus of the sealant increases, the shear failure strength and shear yield strain of SPPJs increase. The increase in sealant thickness reduces the shear failure strength and stiffness of SPPJs. Based on the same shear strain, the increase in the sealant thickness enhances the cumulative energy consumption of SPPJs. The strain concentration zone of the specimens with two sealant layers in unilateral SPPJs becomes larger with the increase in sealant width.

Renovated or replaced? Finding the optimal solution for an existing building considering cumulative CO2 emissions, energy consumption and costs – A case study

The buildings sector is responsible for 37 % of global final energy consumption and nearly 40 % of total direct and indirect CO2 emissions. This has led to promoting renovation efforts to decrease operational emissions of the existing building stock. With decreasing operational emissions, embodied emissions are becoming more important. In new buildings, embodied emissions account for about half of total emissions through the life cycle of a building. If both embodied and operational emissions are considered, renovation often outperforms new constructions, due to high embodied emissions of the structure - especially solid construction with a basement. Based on this, the decision if a building should be renovated or replaced is often not straight forward and depends on various factors. In this paper, a typical German building was considered as a case study, for which both renovation and replacement scenarios were considered, to identify the optimal solutions in terms of overall energy consumption and CO2 emissions of the building in the use phase, the environmental impacts of the building along its entire life cycle, and related costs. Results show that the lowest CO2 emissions during the lifetime of the analyzed building can be achieved with a sustainable replacement building (-2.05 kg CO2/m2/year) by using a heat pump with ground collector coupled with PV. This allows, compared to the existing reference building, reductions of 97 % and 101 % in terms of energy consumption and CO2 emissions, respectively; while natural gas-based technologies are the least targeted and the most volatile to fuels’ prices changes over the years.

Experimental and numerical investigation of the seismic performance of concrete-filled steel tubular composite columns with UHPC plates

To study the seismic performance of concrete-filled steel tubular composite columns with UHPC plates. The pseudo-static tests were carried out on five specimens with the longitudinal distance of the column limbs and thickness of the UHPC plates as test parameters. Subsequently, a nonlinear finite element model of such composite columns was established based on OpenSees, and the calculation method of lateral bearing capacity of the specimen under compression-bending load was proposed. The results showed that the longitudinal distance of the column limbs significantly influenced the lateral bearing capacity as well as the initial stiffness of the specimens. The longitudinal distance of column limbs was increased from 250 mm to 650 mm, and the lateral bearing capacity as well as the initial stiffness of the specimens were increased by 246.0 % and 488.5 %, respectively. The thickness of the UHPC plate was increased from 50 mm to 100 mm, the lateral bearing capacity of the specimen was increased by 32.2 %, while the cumulative hysteretic energy consumption was reduced by 45.05 %. Keeping the same axial pressure ratio, the initial stresses in the column limb steel tubes of the concrete-filled steel tubular composite columns with UHPC plates specimens were higher compared to those of the concrete-filled steel tubular composite columns with ordinary reinforced concrete plates specimens, resulting in poorer ductility. The established nonlinear numerical model accurately captured the hysteretic performance of the specimen. Moreover, the proposed lateral bearing capacity calculation method has high accuracy and can predict the lateral bearing capacity of such structures well.

Vampire: A smart energy meter for synchronous monitoring in a distributed computer system

This paper presents the design and implementation of a low-cost system oriented to the synchronised and real-time surveillance and monitoring of electrical parameters of different computer devices. To measure energy consumption in a computer system, it is proposed to use, instead of a general-purpose wattmeter, one designed ad-hoc and synchronously collects the energy consumption of its various nodes or devices. The implementation of the devised system is based on the confluence of several technologies or tools widely used in the Internet of Things. Thus, this article the intelligent objects are the power meters, whose connections are based on the low-cost ESP32 microcontroller. The message transmission between devices is carried out with the standard message queuing telemetry transport (MQTT) protocol, the measurements are grouped in a database on an InfluxDB server that store the sensor data as time series, and Grafana is used as a graphical user interface. The efficiency of the proposed energy monitoring system is demonstrated by the experimental results of a real application that successfully and synchronously records the voltage, current, active power and cumulative energy consumption of a distributed cluster that includes a total of 60 cores.

Performance of hydrocarbon refrigerants in a refrigerator with liquid line magnet and CNT nano-lubricant

The issues of flammability associated with A3-class hydrocarbon-based refrigerants are controllable by limiting their mass charges. However, these reductions in their mass charge below certain limits deteriorate their performance efficiency. In this experimental study, we analyzed the effects of a liquid line magnetic field (Mag), multi-wall carbon nanotube (CNT) nano-lubricant, and the combination of both (Mag-Nano) on the performance of a very low mass charge (i.e., 30 g) of R600a and LPG refrigerants, as a replacement to the 100 g R134a refrigerant in a domestic refrigeration system. The refrigerants were tested with and without CNT nano-lubricant (pure), two pairs of 3000 Gs liquid line mounted O ring N50 permanent magnets (Mag), 0.2 g/L concentration of CNT nano-lubricant (Nano), and in combination with a liquid line magnetic field and CNT nano-lubricant (Mag-Nano). The performance evaluation of the refrigerants includes the determination of coefficient of performance (COP), evaporator air temperature, volumetric refrigeration capacity, instantaneous power consumption, cumulative energy consumption, and energy cost. A reduction in the COP of R600a and LPG was observed to be about 11–42% and 14–26%, respectively, when compared to R134a. The R134a refrigerant had the lowest evaporator air temperature of −24.5 °C and the highest instantaneous power consumption of 74.6 W. The R600a-Mag-Nano refrigerant is the most efficient option, having the lowest instantaneous power consumption, energy cost, and cumulative energy consumption. The adoption of hydrocarbon refrigerants is more cost-effective than using the R134a refrigerant, resulting in a cost saving of about 8–26%. In conclusion, the proposed methods adopted to enhance the performance of refrigeration system, are very safe and effective.