Recyclable standardized sludge for performance evaluation of low-temperature drying units: Preparation and feasibility verification.

Study on the effect of circulating air volume on the performance of closed loop heat pump drying system

Aiming at the comprehensive evaluation of energy efficiency for large industrial customers, an energy efficiency perception evaluation model based on the gray correlation degree and entropy weight method is proposed in this paper. Firstly, in order to perceive the dynamic energy efficiency of large industrial customers, an energy efficiency measurement model based on the gray correlation degree is established and the weight of energy efficiency evaluation index is determined by entropy weight method. By calculating the correlation between the original value and the optimal value of indexes, energy efficiency measurement results at different time points are obtained. Then, based on energy efficiency measurement results, energy efficiency evaluation results are calculated to determine the customer’s energy efficiency level. Finally, through the case study of a steel plant, the energy efficiency measurement and comprehensive evaluation of four key production links are analyzed, and it is found that the energy efficiency of sintering process 2 has room for improvement.

The motivation of this research project was in response to problems of re-condensation in drying, reduced drying rate encountered by the food and beverage packaging industry which led to the aim of developing a better performing drying system as well as achieving high energy efficiency. A hybrid dryer suited for rapid drying applications is designed, constructed and experimentally tested and considered in atmospheric environment only. The system employs a heat pump in conjunction with a heat reactivated desiccant wheel to provide an efficient drying capability and supply low dew point temperature (DPT) conditions. The combined system utilises the heat dissipated by the condenser in regenerating the desiccant wheel, to increase the economic feasibility of such a hybrid system. Up to 60% heat energy can be saved by using the hybrid system in the rapid surface drying applications. Mathematical models are developed to obtain the correlations among the design operating and performance parameters of the dehumidification systems. The mathematical models can be used to estimate the performance of the hybrid system as well as the performance of the individual components of the system. A prototype model was designed, fabricated and tested. The experimental facility consisted of a heat pump desiccant dehumidifier with the new ecological R134a as a refrigerant which used the heat dissipated by the condenser. An analysis of the experimental data was conducted to determine the practical relationship between the operational parameters (COP, ma and TR) and performance parameters (SMER, DPT and e) of the system. The observed behaviours of the test cases are suggested to be governed by a specific combination of the operation parameters. The analysis shows that the proposed hybrid system can deliver supply air at a much lower DPT compared with the single refrigerant circuit and a desiccant wheel. It is shown that the specific moisture extraction rate (SMER) for conventional dryers is 0.5 - 1 kg/kWh and SMER for heat pump based system is 3 - 4 kg/kWh whereas the hybrid system achieves SMER >5 kg/kWh. By operating the combined system in tandem, a greater amount of dehumidification could be realised due to the improved ratio of latent to the total load. The present research also confirms the importance of improving heat recovery to improve the performance of a heat-pump-assisted drying system.

This article delves into the energy efficiency evaluation methods and carbon emission evaluation methods of cogeneration technology. In terms of energy efficiency evaluation, the concept of energy efficiency and commonly used energy efficiency indicators of cogeneration systems were introduced, such as total energy efficiency, power efficiency, thermal energy efficiency, and fuel utilization efficiency. In terms of carbon emission evaluation, the concept of carbon emissions and commonly used carbon emission indicators for cogeneration systems were analyzed, such as carbon emissions per unit of power generation, carbon emissions per unit of thermal energy, and total carbon emissions. For these evaluation methods, different implementation steps and calculation formulas were introduced in detail, and their application scenarios and advantages and disadvantages were illustrated with examples. These evaluation methods help to evaluate the performance and environmental impact of cogeneration systems, providing scientific basis for relevant decision-making.

The soybean crop in Brazil has been growing in area and productivity in recent years and the analysis of its energy efficiency is very important to guarantee the sustainability of the production system. Assessment of energy efficiency (EE) enables the evaluation of the sustainability of agrosystems, as well as decision-making regarding the reduction in production costs and negative environmental impacts. In this context, the objective of this study was to assess energy efficiency of soybean in different regions of Brazil. For this purpose, 29 areas of soybean across the major producing states were assessed. Energy inputs and outputs of agricultural operations and/or agricultural inputs were calculated by multiplying the amount used by their calorific value or energy coefficient at each stage of production. Energy efficiency was calculated as the ratio between the total output energy and the total input energy during the production process. For every MJ of energy consumed in the production of soybean crop, 6.1; 6.7; 7.1 and 7.2 MJ of energy were produced in the form of grain, respectively in the areas assessed in the Midwest, northeast, southeast and south regions of Brazil. Generally, the main energy expenditure on soybean cultivation in different regions of Brazil was with fertilizers, seeds and herbicides. The adverse weather conditions of the year / harvest evaluated in the south-central region of Brazil resulted in low soybean yields and consequently resulted in lower energy efficiency in these regions. The evaluation of energy efficiency in soybean crops to be representative must be carried out in different regions and edaphoclimatic conditions.

Energy Efficiency Analysis and Evaluation of GSHP in Operation

Software testing is a critical phase in information system development to ensure the system's quality and reliability. This study aims to evaluate the reliability and functionality of PT Perta Sakti Abadi's financial information system using the black-box testing method with the Equivalence Partitioning (EP) technique. This technique allows input data to be grouped into valid and invalid categories, minimizing test cases without reducing testing coverage. The testing focuses on the login feature as the system's primary component by evaluating various input combinations. The testing scenarios include boundary conditions to ensure the system handles inputs correctly in various situations.The results indicate that the system successfully verifies valid credentials, rejects access with invalid data, and provides informative error messages. Additionally, the system demonstrates resilience in handling testing scenarios, including inputs with special characters and empty fields. Input validation mechanisms function optimally, supporting secure user access and ensuring the login feature aligns with functional specifications. This successful testing forms a strong foundation for testing other modules, such as multi-level authentication and data encryption. Thus, the Equivalence Partitioning technique within the black-box testing method proves effective in enhancing the quality of web-based financial information systems.

Novel waste heat recovery-assisted heat pump dryer is designed, developed, and experimented in different operating modes. Energy, exergy, economic, and exergoeconomic parameters of the dryer with and without waste heat recovery are experimentally compared. Radish chips are dried to remove moisture from 93.5% to 10.5% at fixed dryer inlet air velocity. Both energy and exergy efficiencies are found highest for the waste heat recovery-assisted (hybrid) system (56.26% and 35.9%, respectively). Specific moisture extraction rate (2.4 kg/kWh) and coefficient of performance (6.72) are highest for the hybrid system. The payback period for the hybrid system over the simple system is 33 months. The lowest exergoeconomic factor is for expansion devices in both simple and hybrid systems (0.0918 and 0.1348, respectively). Total exergy destruction costs for simple and hybrid systems are 0.10148 and 0.1266 $/h, respectively. The most important component that needs to improve based on the exergoeconomic factor is the drying chamber. Practical applications In the present study, a novel heat pump dryer assisted with waste heat recovery from the diesel engine is designed and developed. Various energy, exergy, economic, and exergoeconomic performance parameters with and without waste heat recovery are experimentally compared. To check the applicability, the radish chips have been dried to remove moisture from 93.5% to 10.5% at fixed dryer inlet air velocity. The testing shows that the proposed system is superior as compared to the simple heat pump dryer in terms of both energy and exergy efficiencies, specific moisture extraction rate, and overall heating coefficient of performance. The payback period for the proposed system over a simple one is found 3 years approximately. The proposed system can be a futuristic and promising solution for the drying applications, which satisfies two purposes: An effective way to utilize the engine waste heat and superior system performance.

A review of energy efficiency evaluation technologies in cloud data centers

A lot of agricultural residues and wastes generated in the country are improperly utilized and poorly managed. The bulk is left to decompose or blazed, resulting in environmental pollution and degradation. Studies have shown that briquetting provides a means of managing this waste as fuels however, energy efficiency of this process has not been investigated extensively. This study investigated the energy efficiency associated with combustion of selected briquettes-derived agro-waste. An experimental design was adopted that involved comparing the energy efficiency from the combustion of biomass briquettes of sawdust (SD) from different trees, rice husk (RH), coconut shell (CS) and corncob (CC) with paper (p) and starch (s) binders with wood (control). Energy parameters which include calorific value (CV), bulk density (BD), and energy density (ED) were measured. Energy efficiency parameters such as water boiling time (WBT), Mass of biomass used (MB), Burning Time (BT), Burning rate (BR) and Recoverable energy (RE) from the combustion of 0.5kg mass of each of the briquette treatments in comparison with the wood was obtained. The energy parameters of the biomass briquettes ranged 12.3 – 19.6 kJ/g, 0.27 – 0.75 g/cm3 and 3.9 – 13 KJ/cm3 for CV, BD and ED respectively. The ranges of the thermal properties based on the water boiling test carried out included water boiling time, mass of biomass used and burning time were 7.75 – 62.5 min, 150 – 390 g and 53.5 – 143 min respectively. Although sawdust briquettes took least time to boil water, coconut briquettes burned efficiently in terms of material conservation and duration of burning. Therefore coconut and sawdust briquettes are both viable alternative fuel sources to firewood.

Heat pump drying in the food industry is notable for its efficiency and energy savings. When designing a date fruit drying machine, it is crucial to consider heat transfer characteristics and performance, measured by parameters such as the coefficient of performance (COP), specific energy consumption (SEC), and specific moisture extraction rate (SMER). This study compares the performance of R-22 and R-1234yf in terms of energy efficiency and drying capacity for a date drying machine operating at a drying temperature of 60°C to dry 20 kg of dates per hour, under environmental conditions of 26°C. Results show that the machine the COP using R-1234yf is 3.449, slightly lower than R-22’s COP of 3.894, indicating that R-22 is more energy efficient. The specific energy consumption (SEC) with R-1234yf is 0.014 kWh/kg, compared to R-22’s 0.013 kWh/kg, while the specific moisture extraction rate (SMER) for R-22 is 75.216 kg/kWh, higher than that of R-1234yf at 69.614 kg/kWh. These findings suggest that although R-22 has superior efficiency, R-1234yf provides a competitive alternative, especially considering its significantly lower global warming potential (GWP). Thus, R-1234yf is a practical and environmentally friendly choice for date drying applications, supporting the transition towards more sustainable refrigerant options.

This paper investigates the trade-off between energy efficiency and spectral efficiency in multi-cell massive MIMO systems. The relevance of the study is driven by the need to simultaneously increase throughput and reduce the energy consumption of base stations in next-generation wireless networks, given the growing number of antennas and served users. The purpose of the study is to determine how the number of base-station antennas, the number of served users, linear signal processing schemes, and hardware implementation parameters affect the energy efficiency of multi-cell massive MIMO systems, and to identify configurations that provide the best trade-off between energy and spectral efficiency. Methods. A mathematical model of a massive MIMO system is developed, taking into account the number of base station antennas M, the number of user equipment K, and various linear signal processing schemes, including MR, ZF, RZF, S-MMSE, and M-MMSE. The model incorporates power consumption parameters reflecting hardware implementation characteristics, represented by two different sets of component specifications. The evaluation of energy and spectral efficiency is carried out using simulation-based analysis for various system configurations. Results. The results show that an optimal antenna-to-user ratio of M/K ≈ 3–4 achieves maximum energy efficiency without a significant reduction in spectral efficiency. It is demonstrated that the M-MMSE and S-MMSE algorithms provide the highest energy efficiency performance with moderate computational complexity, particularly when improved hardware components are employed. The obtained results confirm the existence of a pronounced energy efficiency optimum as the number of base station antennas increases . The novelty of this work lies in the comprehensive analysis of the energy–spectral efficiency trade-off in multi-cell massive MIMO systems while jointly accounting for linear signal processing schemes and hardware implementation parameters, which enables the formulation of practical recommendations for base station configuration under technological constraints. Practical significance. The findings of this study can be applied to the design and optimization of energy-efficient multi-cell massive MIMO systems for next-generation wireless communication networks, taking into account hardware implementation constraints and quality-of-service requirements.

Energy efficiency evaluation based on DEA integrated factor analysis in ethylene production

Dehydration or drying is one of the ubiquitous, often most energy-intensive, processes in various industrial, residential, and commercial applications, reflecting a large energy market size in the industrial and residential sectors. Conventional dryer systems utilizing either electric resistance elements or more commonly fossil fuels such as natural gas with a maximum COP (Coefficient of Performance) of 1 suffer from low energy efficiency. Existing condensing dehydration systems including heat pump dryers, however, need to significantly cool the air to achieve dehumidification. The added cooling and subsequent heating to return the air to the desired drying temperature consume substantial energy and thus reduce drying performance. As such, state-of-the-art fuel-driven clothes dryers suffer from sensible and latent (i.e., humidity) losses, mainly due to enthalpy losses associated with warm humid air leaving the dryer. The energy efficiency of a clothes dryer system can be potentially improved if part of the thermal energy, currently wasted, is captured. This dissertation introduces a novel sorption-based drying concept to overcome shortcomings that deteriorate energy efficiency in existing gas, electric, or heat pump dryer systems. The system employs a liquid-desiccant solution to directly capture air humidity, thereby allowing circulation of the air in a closed loop to achieve high drying energy efficiency. In other words, the system captures waste latent heat from the moisture produced during the dehydration process and reuses it to improve energy efficiency. First, a comprehensive quasi-steady-state thermodynamic modeling is developed to predict transient response and overall drying performance (i.e., time and energy metrics) of the proposed sorption-based dehydration concept employed for a clothes dryer application. The developed model considers the details of both the dryer unit and the sorption cycle. The analysis showed a drying time of 44 minutes and a specific moisture extraction rate (SMER) of 1.71 kgwater/kWh, reflecting a 112% energy improvement compared with stateof-the-art gas clothes dryers. The promising results showed the potential of the sorptionbased dehydration system to take advantage of the available waste thermal energy and improve energy efficiency.At the heart of the proposed sorption-based drying system, a liquid-desiccant-based dehumidifier module is responsible for the dehumidification process. Existing liquiddesiccant-based air dehumidification systems suffer from a poor liquid flow distribution which deteriorates their moisture removal rate. In the proposed dehumidifier, the capillary forces and wickability effect of textured surfaces are altered to minimize the liquiddesiccant flow rate of the fully wetted state, thereby transforming the physics of interfacial desiccant flow distribution.

The purpose of this study is to investigate the effect of drying parameters on drying performance in an air-vented tumble dryer, and to optimize its drying performance by adjusting parameters. The critical drying parameters that influenced specific moisture extraction rate (SMER), final moisture content, evenness of drying, and smoothness appearance were determined by the analysis of variance in JMP software, which were rotational speed of the motor and load size, with clearly significant individual effects and binary interactions. In order to improve the applicability of the outcomes obtained in this study and to take into account the interactions between drying parameters and drum structure parameters on drying efficiency, non-dimensional analysis was used and the correlation between drying efficiency and dimensionless variables was studied. The Buckingham Pi theorem was applied to the problem to derive dimensionless Pi terms upon which the drying efficiency depends. A step regression analysis was then conducted to test the assumption that SMER was influenced by the dimensionless parameters based on the standard least squares fitting. Results indicated that the regression model showed an explanatory power of 73.8%. By adjusting the dimensionless parameters in the model, an optimized energy-saving drying program was obtained with the desirability goal of reducing the value of SMER. Compared with the original program, energy efficiency was improved by 32.4%.