Energy Efficiency Coefficient Research Articles

Productivity and nutritional value of perennial cereal grasses in the Middle Cis-Urals

The purpose of the research was the assessment of feed productivity and nutritional value of 13 new varieties of meadow timothy, meadow fescue and awnless brome when cultivated for green mass in the Middle Cis-Urals. The research was carried out in 2018–2022 on sod-podzolic medium loamy soil of the Udmurt Republic. Meteorological conditions of the growing seasons during the years of the research were different: 2018, 2021 and 2022 were arid (hydrothermal coefficient – 0.89, 0.78 and 0.91, respectively), 2020 – slightly arid (HTC – 1.04), 2019 – waterlogged (HTC – 1.73). The beginning of regrowth of the studied varieties of perennial cereal grasses was noted in the third ten days of April; the grass reached mowing ripeness in 44–60 days. The yield of meadow timothy varieties on average for three years of using the grass stand was at the level of 3.5–3.9 t/ha of dry weight, meadow fescue – 2.3–2.4 t/ha, awnless brome – 4.5–4.7 t/ha. The “year conditions” factor had a primary influence on the variation in yield, density and height of the grass stand – 92.4…97.4 %, 62.9…79.2, 80.3…82.6 %, respectively. The “genotype x year” factor also influenced the number of shoots and their height. Fescue varieties were distinguished by a relatively high content of crude fat (2.5–3.1 %), sugars (15.6–17.7 %), and calcium (0.31–0.36 %). High content of crude fat (2.3–2.6 %), phosphorus (0.68–0.71 %), potassium (2.45–2.52 %), calcium (0.31–0.39 %) noted in plant samples of awnless brome varieties. A positive strong correlation between the yield of dry mass of cereal grasses and the content of phosphorus (r = 0.87…0.96) and potassium (r = 0.69…0.85) in it was revealed. Some varieties of perennial cereal grasses were distinguished by their nutritional value: meadow timothy varieties Sleipnir (Finland), Aturo (Germany) and Tamiza (Germany) with a yield per 1 hectare of metabolic energy of 32.3–34.4 GJ, digestible protein – 0.14–0.16 tons, feed units – 2.41–2.60 thousand; meadow fescue variety Karpatchi (Netherlands) – 21.2 GJ, 0.09 tons, 1.57 thousand; awnless brome variety Gvardeets (Russia) – 35.7 GJ, 0.25 tons and 2.58 thousand, respectively. Cultivation of Karpatchi fescue, Sleipnir timothy and Gvardeets brome is energetically and economically profitable: energy efficiency coefficient – 1.9; 3.0 and 3.6, profitability level – 65; 101 and 161 %, respectively.

Productivity of crop rotations with different types of fallow and their effect on the humus content in sod-podzolic soil the Middle Urals

The research was carried out in the conditions of the Perm Region on sod-podzolic heavy loamy soils in a long stationary plot trial, laid down in 1977. The purpose of the research is to study the effect of various types of fallow on crop rotation productivity and humus content in the soil. The data are given for two rotations (2009–2022) of fallow-grain–grass crop rotations with various types of fallow – with manurial, sown with clover, sown with melilot, sideral with clover and sideral with melilot – without mineral fertilizers and with fertilizers (N60P30K60). It was found that in the sown fallows, the mass of root and mowing plant residues of meadow clover and yellow melilot, depending on the nutrition background, reaches 4.08–4.36 t/ha with a nitrogen content of 41.8–46.9 kg/ha, phosphorus 16.7–18.6 kg/ha and potassium 42.7–69.6 kg/ha. In sideral fallow with clover and clover biomass, 6.99–9.04 t/ha and 6.83–8.53 t/ha of dry matter with a content of 133.5–148.1 kg/ha of nitrogen, 34.3–41.2 phosphorus and 121.2–148.9 potassium were supplied to the soil, respectively. The application of organic fertilizers in the fallow field contributed to an increase in the humus content by 0.19 abs.% to the initial (2.04 %) in the variant without mineral fertilizers and by 0.69 abs.% in the variant with the introduction of mineral fertilizers to the initial (2.08 %) Clover sideral fallow also contributed to an increase in the humus content in the soil by – 0.38–0.52 abs.%. There was an increased productivity of crop rotation with sideral melilot fallow (2.22–2.25 t/ha of grain units per year) relative to the traditional crop rotation with pure fallow (2.08–2.11 t/ha of grain units per year). Cultivation of crops in all studied crop rotations was energetically efficient, the energy efficiency coefficient was 3.63...4.48 in the variants without mineral fertilizers, against the background of NRK – 2.38...3.21.

Оценка эффективности смесей фестулолиума с люцерной в лесостепи Приобья (Западная Сибирь)

The results of the research of festulolium and alfalfa in a joint herbage with different methods of sowing and doses of mineral nitrogen conducted in the forest-steppe of Western Siberia in the period from 2020–2023 are presented. The growth and development of crops in the initial period of life, winter hardiness, productivity and economic feasibility of cultivation were taken into account both in favorable 2019–2021 (HTC = 1.0...1.29) and in unfavorable 2022–2023 (HTC = 0.6...0.99). A high response of perennial grasses was achieved in sowing festulolium one row + alfalfa three rows — 38.13 t/ha of green mass, which corresponds to a single-species alfalfa crop. Sowing with a mixture of seeds is 21% less productive. A positive effect was obtained from optimizing the level of cenosis and foliage of alfalfa by 56%, which was confirmed by an average correlation (r = 0.58). The energy efficiency coefficient (CEE) had maximum values of 9.8–11.7 and was characterized as high, the profitability of cultivating mixtures was 407–465%. A positive effect was obtained when N30 was introduced into the sowing of festulolium one row + alfalfa three rows — 21–36% to 37.41 t/ha of green mass. In comparison with the unfavorable background, the share of festulolium in the yield of mixtures increased to 58–71%, alfalfa decreased to 29–42%. CEE = 4.9–5.6 (the value is from medium to high), the profitability of cultivating mixtures is 325–378%. The application of mineral nitrogen N60 to joint crops of festulolium and alfalfa increases the collection of green mass compared with single-species sowing of festulolium by 10–20%, to 34.74–37.93 t/ha of green mass due to the maximum proportion of cereals in mixtures — 62–80% with its responsiveness to fertilization. CEE = 4.5–4.9 (average value), the profitability of cultivating mixtures is 323–365%.

Study on performance of direct-expansion heat pump water heater integrating uninsulated micro-channel PV/T solar collector

In this paper, a direct-expansion heat pump water heater system integrating uninsulated micro-channel PV/T solar collector is proposed. This system can realize storage for both thermal energy and electricity and complementary grade, ensuring the supply of domestic hot water. Based on the performance of the micro-channel PV/T heat pump water heater system, the theoretical models of micro-channel PV/T solar collector, hot water storage tank, compressor and electronic expansion valve are established where R134a is used as refrigerant. Theoretical simulation and analysis of system performance under different solar radiation intensities, ambient temperatures and different outdoor wind speeds are carried out with MATLAB. The results show that solar radiation intensity has the greatest influence on the system performance, followed by ambient temperature and wind speed. The basic-thermal system performance coefficient (COP) and the advanced system performance coefficient (COPpvt) will be enhanced, while the required operating time will be reduced, as solar radiation intensity and ambient temperature increase. This system removes the thermal insulation for the micro-channel PV/T solar collector that the convection heat transfer on the micro-channel evaporator is enhanced. Therefore, the system can absorb the thermal energy from the ambient air according to different solar radiation intensities, and maintain a high coefficient of performance, electric efficiency, thermal efficiency and overall energy efficiency. Even when the solar irradiation is 322 W/m2 and the ambient temperature is −18.6 °C, the thermal efficiency, electric efficiency and overall energy efficiency of UMC-PVT-SC and COPpvt can still remain at 0.718, 0.2442, 1.341 and 5.63, ensuring the heating capacity and high grade power output capacity.

Complex Use of the Main Marine Diesel Engine High- and Low-Temperature Waste Heat in the Organic Rankine Cycle

The decarbonization problem of maritime transport and new restrictions on CO2 emissions (MARPOL Annex VI Chapter 4, COM (2021)562) have prompted the development and practical implementation of new decarbonization solutions. One of them, along with the use of renewable fuels, is the waste heat recovery of secondary heat sources from a ship’s main engine, whose energy potential reaches 45–55%. The organic Rankine cycle (ORC), which uses low-boiling organic working fluids, is considered one of the most promising and energy-efficient solutions for ship conditions. However, there remains uncertainty when choosing a rational cycle configuration, taking into account the energy consumption efficiency indicators of various low-temperature (cylinder cooling jacket and scavenging air cooling) and high-temperature (exhaust gas) secondary heat source combinations while the engine operates within the operational load range. It is also rational, especially at the initial stage, to evaluate possible constraints of ship technological systems for ORC implementation on the ship. The numerical investigation of these practical aspects of ORC applicability was conducted with widely used marine medium-speed diesel engines, such as the Wartsila 12V46F. Comprehensive waste heat recovery of all secondary heat sources in ORC provides a potential increase in the energy efficiency of the main engine by 13.5% to 21% in the engine load range of 100% to 25% of nominal power, while individual heat sources only achieve 3% to 8%. The average increase in energy efficiency over the operating cycle according to test cycles for the type approval engines ranges from 8% to 15% compared to 3% to 6.5%. From a practical implementation perspective, the most attractive potential for energy recovery is from the scavenging air cooling system, which, both separately (5% compared to 6.5% during the engine’s operating cycle) and in conjunction with other WHR sources, approaches the highest level of exhaust gas potential. The choice of a rational ORC structure for WHR composition allowed for achieving a waste heat recovery system energy efficiency coefficient of 15%. Based on the studied experimental and analytical relationships between the ORC (generated mechanical energy) energy performance (Pturb) and the technological constraints of shipboard systems (Gw), ranges for the use of secondary heat sources in diesel operational characteristic modes have been identified according to technological limits.

Numerical investigation on the heat storage/heat release performance enhancement of phase change cemented paste backfill body with using casing-type heat pipe heat exchangers

Cemented paste backfill mining technology that recycling tailings and waste rocks can effectively reduce heat damage. Heat pipe exchangers, demonstrating much higher thermal conductivity than water pipe exchangers, led to the development of a novel phase change backfill body system with a built-in casing heat pipe exchanger (HP-PCB). Numerical analysis revealed that, for the melt and solidification of a large amount of PCM, the temperature step phenomenon was observed at both heat storage and heat storage/heat release coexistence stages. Increased surrounding rock temperatures enhanced heat storage and heat release capacities, but reduced system energy efficiency. The optimal water flow velocity was identified at the laminar-turbulent transition flow rate, 0.32 m/s. An increase in water inlet temperature resulted in lower heat release capacity and system energy efficiency. The energy efficiency of the HP-PCB system exceeded that of the traditional water pipe-backfill system by 37.22%. At a surrounding rock temperature of 45 °C, cooling water velocity of 0.32 m/s, and a 6 °C inlet water temperature, the HP-PCB system achieved its highest energy efficiency coefficient, 86.38%. These findings highlight the HP-PCB system potential for efficient geothermal energy extraction in mine.

EN Improving the energy efficiency of refrigeration equipment with a direct sales function

The increased use of refrigerants with low global warming potential GWP over the past decade indicates that manufacturers are already making gradual replacements with refrigerants with reduced environmental impact. Thus, in addition to HFC gas phase-out requirements, most EU countries are pursuing a trend to reduce the energy consumption of refrigeration appliances. Such countries restrict the import of equipment that does not meet the energy efficiency requirements. This paper presents the ecodesign of refrigeration equipment in relation to the requirements of the sales market using the Regulation on Conformity Assessment Procedure. HVAC&R equipment contributes to GHG emissions in two ways: directly through refrigerant leakage or venting, and indirectly through electricity use, the latter accounting for up to two-thirds of GHG emissions. The paper compares the energy and environmental characteristics of refrigerants R404a and R290 in freezer M200V. The experimental results show that the highest COP va­lues in the system for R404a and R290 are 3.02 and 3.19, respectively. Possibilities of complete transition from F-gases to natural analogues with GWP ≈ 0 are shown. At application of R290 its advantages on energy efficiency are obvious - reduction of electric power consumption of freezing chests on 8,9 %, influence on environment R404A – GWP=3260, R290 – GWP=3. The calculation of energy efficiency class for freezing chest was made. To improve energy efficiency, a number of design modifications were made: the density of the thermal insulation material and the compressor were changed. The energy consumption of the modified version at the second climatic class was measured at 1.23 kW/24h, and the energy efficiency coefficient according to the calculation EEI =34.904, which corresponds to the energy efficiency class «C».

ECONOMIC AND ENERGY EFFICIENCY OF PEA INOCULATION WHEN GROWING CROP IN THE SYSTEM OF ORGANIC PRODUCTION

Objective. To analyse economic and energy efficiency of inoculants based on a new strain Rhizobium leguminosarum Г222 in the technology of growing field peas. Methods. The calculation of the indicators of the economic efficiency of the cultivation of field peas for various seed treatment variants was carried out using methods and commonly used methodological approaches, which are based on a comparison of the results of the application of a certain agricultural measure with the costs of its implementation. The following indicators were studied: profit, cost per unit, payback of additional costs, as well as the level of profitability of production. Modelling of technological costs in the conditions of production scales using typical pea growing technologies has been used. The main agrotechnical operations have been modelled according to resource cost standards and product costing algorithms with the inclusion of additional operations and costs associated with the use of studied inoculants. In order to calculate the main indicators of the energy efficiency of the applied means for treatment of the pea seeds, the costs of all types of used resources and the obtained products were converted into energy equivalents according to generally accepted methods. Results. The use of inoculants based on R. leguminosarum Г222 contributes to increase in all the main indicators of economic efficiency: cost per unit, profit based on 1 ha of sown area and the level of profitability increase with the corresponding level of payback of additional costs. This is due to the higher rates of yield growth (and, accordingly, cash receipts) in experimental variants compared to the rates of increase of costs per unit area associated with the use of inoculants. According to the results of the energy efficiency analysis, it has been shown that the inoculation of peas with a new strain provides a high level of energy efficiency in terms of the ratio of the energy content of the obtained products to the energy consumption for its production (energy efficiency coefficient). The results of the comparative analysis of the calculated indicators show that in the variants with bacterization, there is a significant lag in the rates of increase of anthropogenic energy consumption per 1 ha of sown area versus the increase in yield and energy content of the obtained products. Additional energy costs associated with the use of inoculants are 8.00–24.39 times paid back by the energy of the additional harvest. Conclusion. The results of the analysis suggest high economic and energy efficiency of the use of the new strain R. leguminosarum Г222. The variant in which the use of R. leguminosarum Г222 was combined with a polysaccharide-protein complex is the most efficient.

Development and enhancement in drying performance of a novel portable greenhouse solar dryer

The increasing demand for drying technology for agriculture and food products has gained significant attention due to population explosion and inadequate resources available. The present study focuses on the concept of enhancing the drying performance of portable greenhouse solar dryer. The experimental investigations for evaluating the dryer performance were carried out while drying out onion slices. The experimentation was carried out in 4 different modes to demonstrate the effect of various modifications implemented to improve the dryer performance. The active greenhouse solar dryer (AGHSD) is the first working mode which comprises of the conventional drying system with active mode of removing moisture. The second working mode uses recirculating fans along with exhaust fans (AGHSD@circulating fans). In the third working mode an Evacuated Tube-type solar Air Heater was added to along with previous modification (AGHSD@circulating fans + ETAH). The last working mode adds an air flow distribution system to the incoming pre heated air from the Evacuated Tube-type solar Air Heater (AGHSD@circulating fans + ETAH + air flow system). Various performance characteristics like moisture ratio, heat utilization factor, coefficient of energy, heat gain and thermal efficiency of the dryer are used to analyze the changes in the drying performance. AGHSD@circulating fans + ETAH + air flow system reduced the moisture ratio in the onion slices to 5.32% from 95% in one day, compared to 19.99% for AGHSD and 46% for open sun drying. The heat utilization factor and coefficient of energy for AGHSD@circulating fans + ETAH + air flow system and AGHSD@circulating fans + ETAH improve by 10% and 15% respectively as compared to AGHSD. AGHSD@circulating fans + ETAH + air flow system shows improved heat gain of 29.53% and shows the best drying rate for the developed drying system. The thermal efficiency of AGHSD@circulating fans + ETAH + air flow system is around 60% while for AGHSD is around 41% which is higher than the thermal efficiency of 20% for sundried samples.

Efficiency of sugar beet cultivation in the Steppe of Ukraine

Purpose. To determine the features of the economic and energy efficiency of growing sugar beet in the Steppe of Ukraine. Methods. Field research was conducted during 2020–2022 in the Chkalov Agrocompany LLC (Kirovohrad region). The scheme of the experiment provided for the cultivation of sugar beet against the background of the use of a water-retaining agent (without hydrogel; hydrogel Aquasorb, 300 kg/ha), under application of different fertilizers (without fertilizers – control; manure, 20 t/ha; N170P180K350; Leonardyt, 400 kg/ha; Parostok 20, 400 kg/ha) and foliar application of fertilizers during the growing season (without foliar feeding; Humifild SE, 2 kg/ha in the BBCH stage 30 and 39). Organic and mineral fertilizers (PK) were applied in autumn at ploughing and nitrogen was applied at cultivation in early spring. The water-retainer was applied to the soil two weeks before sowing the crop in the zone of the row, based on the data of the GPS tracker. The rest of the agricultural activities corresponded to the generally accepted crop cultivation technology in the area of research. The calculation of economic indicators was performed using prices of 2023. Results. In terms of income from the sale of sugar beet roots, the best treatment was the use of Aquasorb hydrogel, fertilization of sugar beet with Leonardyt and foliar application of fertilizer Humifild, where 106.8 thousand UAH/ha was obtained. In terms of costs for crop cultivation technology, the most expensive treatment was the application of mineral fertilizers (75.9–84.4 thousand UAH/ha). In contrast, application of new organic fertilizers provided better results in terms of the costs of growing sugar beet. In particular, in the treatments where hydrogel was not applied, the costs of fertilization with Leonardyt were 37.3–39.8 thousand UAH/ha, while with the use of Aquasorb, the treatment with Leonardyt had a cost of 43.3–45.8 thousand UAH /ha. On the other hand, the costs of using organic fertilizer Parostok were 39.6–42.1 and 45.6–48.1 thousand UAH/ha. In the treatment with Parostok followed by foliar application of Humifild, a profit of UAH 60.6 thousand/ha was obtained. In case of application of Aquasorb hydrogel and fertilization with Leonardyt fertilizer followed by foliar feeding with Humifild, a profit of UAH 61,00 per 1 ha was obtained, which was the maximum in the experiment. Profitability of 145.0% was obtained with the application of Parostok 20 fertilizer and 143.8% with Humifild applied against the background of Parostok. In the treatment with Leonardyt, the profitability was 142.6%. With the use of Aquasorb hydrogel and Leonardyt fertilizer, the level of profitability was somewhat lower and proportional to the increase in technology costs (133.2%). Conclusions. In the case of applying Aquasorb hydrogel (300 kg/ha) to the row zone before sowing and fertilizing sugar beet with Leonardyt or Parostok 20, more than 300 GJ/ha of energy yield was obtained. The maximum accumulation of energy in the harvest (312.5 GJ/ha) was obtained in the treatment where moisture retainer, Parostok 20, and Humifild were applied. When Parostok 20 was used as the main fertilizer, the coefficient of energy efficiency was 4.70, while with foliar application of Humifild it was 4.72. In the treatments where moisture retainer and Parostok 20 were applied, with or without subsequent foliar application of Humifild, the coefficient of energy efficiency was 4.60 and 4.63, respectively.

Анализ урожайности сортов горчицы сарептской в условиях приазовской зоны Ростовской области

The article presents the results of research on the study of morphological and production indicators of mustard Sarepta in the conditions of the Azov zone of the Rostov region. It was found that among the studied varieties of mustard Sarepta, the best indicators were in the varieties Lux and Lera, forming a seed yield of 11.0 and 10.56 c / ha, respectively. The coefficient of energy efficiency of growing these varieties was 1.56 and 1.53. The increase in energy in the yield of dry matter was in the range of 10.56–11.04 MJ/ha, which is more than that of the standard Donskaya 8 variety by 1.64 and 1.02 GJ/ha, respectively. Keywords: SAREPTA MUSTARD, VEGETATION PHASES, BIOLOGICAL YIELD, ENERGY EFFICIENCY, ENERGY GAIN

Efficiency Modeling using the Mirror Surface of Heliostats in a Solar Power Tower

Analyzing the geographical location and climatic conditions of Turkmenistan, we conclude that solar energy is a priority among all renewable sources since the duration of sunny days in the country is from 270 to 320 days a year. Development, creation of large-scale solar power plants and use in remote desert regions of Turkmenistan is an urgent problem. The article considers the possibilities of creating a solar power plant based on a tower-type layout. The modes of the optical system in the natural and climatic conditions of Turkmenistan are calculated using a mathematical model, the coefficient of efficiency of using the mirror surface of the installation and the distribution of the level of instantaneous local values are determined. Figure 1 shows the movement of the Sun in the sky, which varies depending on the time of year. The results of the study show that the maximum increase in the energy efficiency coefficient can be achieved with the location of solar panels perpendicular to solar radiation with the dense placement of heliostats on the north side of the tower, then energy efficiency will increase by 25-40% in summer and 10-15% in winter.

CURRENT TRENDS IN THE DEVELOPMENT OF AGRICULTURAL SYSTEMS IN THE UDMURT REPUBLIC

Minimisation of soil tillage is one of the defining trends in the development of agriculture. It allows for a significant reduction in agrotechnical operations in crop cultivation, thereby reducing the technological load on soils, energy, and labour inputs in production and increasing soil resistance to erosion processes. Minimum tillage effectively promotes the restoration of potential and adequate soil fertility and aligns with the principles of adaptive landscape agriculture. Despite numerous positive aspects of minimum tillage, its implementation in production is restrained by certain drawbacks: worsening of crop phytosanitary conditions, increased plough layer density, differentiation of the plough layer by agrochemical and agrophysical indicators, and more. To assess the possibility of implementing minimum tillage in the soil and climatic conditions of the Udmurt Republic, long-term field experiments have been conducted at the Udmurt Research Institute of Agriculture since 1980. Both positive and negative aspects of three types of primary soil tillage have been identified. Moldboard ploughing, throughout the observation period, compared to other types of tillage, provided the highest crop yield (by 0.15 0.50 t per hectare or 5.6 17.5%) and energy efficiency coefficient (by 1.9 16.7%). No-till soil treatment proved to be the most environmentally friendly, increasing the organic matter content in the 0-10 cm layer by 8.1 11.5%. However, it led to a strong differentiation of the plough layer into two sub-layers: 0-10 and 10-20 cm. The lower sub-layer was characterised by higher density and lower content of mineral nutrients and humus. In most cases, combined tillage showed intermediate results. Further scientific research is needed to develop agrotechnologies with more significant minimisation of soil tillage.

Solar power plant based on a tower-type layout

I suggest the following abstract: In Turkmenistan, the solar energy is a priority among all renewable sources since the duration of sunny days in the country is from 270 to 320 days a year. The article considers the possibilities of creating a solar power plant based on a tower-type layout. The modes of the optical system in the natural and climatic conditions of Turkmenistan are calculated using a mathematical model, the coefficient of efficiency of using the mirror surface of the installation and the distribution of the level of instantaneous local values are determined. The results of the study show that the maximum increase in the energy efficiency coefficient can be achieved with the location of solar panels perpendicular to solar radiation with the dense placement of heliostats on the north side of the tower, then energy efficiency will increase by 25-40% in summer and 10-15% in winter.

Comparative studies and optimizations of air distribution of underground building ventilation systems based on response surface methodology: A case study

As underground enclosed buildings, utility tunnels have limited ventilation conditions. An efficient ventilation system is necessary for improving the indoor thermal environment and air quality in utility tunnels. In this paper, exhaust fan ventilation (EFV), relay fan ventilation (RFV), and innovative wall-attached ventilation (WAV) schemes are compared using a series of evaluation indicators (i.e., energy efficiency coefficient, nonuniform coefficient, temperature not guaranteed rate, and age of air). The results show that the WAV scheme offers a higher ventilation efficiency, while decreasing the age of air and providing a uniform air distribution. Thus, the WAV scheme is recommended for utility tunnel ventilation systems. Additionally, the WAV scheme is further optimized and analysed based on response surface methodology (RSM). The influence of different factors (i.e., the slot outlet height (h), slot outlet width (b), air-supply velocity (u0), and cable heat source intensity (q)) on the evaluation indicators is studied, and the optimal design scheme (h = 1.40 m, b = 0.12 m, u0 = 3.00 m/s, q = 74.5 W/m2) is obtained and verified. The age of air in the optimal design scheme is 486.50 s. This paper can provide a reference for the ventilation design of urban underground buildings.

Modeling the Energy Consumption of R600a Gas in a Refrigeration System with New Explainable Artificial Intelligence Methods Based on Hybrid Optimization.

Refrigerant gases, an essential cooling system component, are used in different processes according to their thermophysical properties and energy consumption values. The low global warming potential and energy consumption values of refrigerant gases are primarily preferred in terms of use. Recently, studies on modeling properties such as compressor energy consumption, efficiency coefficient, exergy, and thermophysical properties of refrigerants in refrigeration systems with artificial intelligence methods has become increasingly common. In this study, a hybrid-optimization-based artificial intelligence classification method is applied for the first time to produce explainable, interpretable, and transparent models of compressor energy consumption in a vapor compression refrigeration system operating with R600a refrigerant gas. This methodological innovation obtains models that determine the energy consumption values of R600a gas according to the operating parameters. From these models, the operating conditions with the lowest energy consumption are automatically revealed. The innovative artificial intelligence method applied for the energy consumption value determines the system's energy consumption according to the operating temperatures and pressures of the evaporator and condenser unit. When the obtained energy consumption model results were compared with the experimental results, it was seen that it had an accuracy of 84.4%. From this explainable artificial intelligence method, which is applied for the first time in the field of refrigerant gas, the most suitable operating conditions that can be achieved based on the minimum, medium, and maximum energy consumption ranges of different refrigerant gases can be determined.

(Invited) A Critical Review on the Expressions of Energy Efficiency Used in Low Temperature Water Electrolysis

The accurate knowledge of the energy efficiency coefficient of low temperature water electrolysis (Alkaline, PEM or AEM Electrolyzer) is a critical-point to estimate the total cost of electrolytic hydrogen production. After describing the fundamentals of these three processes and presenting the main data of water electro-dissociation under given temperature and pressure conditions, the energy efficiency coefficient can be calculated at the Laboratory scale by taking the ratio of the theoretical energy (ΔH) to decompose water under equilibrium conditions (no current) to the real energy used (ΔH + energy losses) to electrolyze water at a given current intensity. Different approximations of this coefficient are discussed and compared to data from literature. Conversely in the industry this coefficient can be calculated by taking the ratio of the total energy of hydrogen collected at the exhaust of the electrolyzer to the total energy (electricity + heat) supplied to the complete system. It is demonstrated that both definitions are consistent and similar if all the energy involved is taken into account. It is also shown that some approximations, in particular those neglecting the thermal energy in the denominator of this ratio, give efficiency coefficients larger than unity for cell voltages lower than the thermo-neutral voltage, which is a thermodynamic non-sense.The next figure shows the plot of the theoretical energy efficiency coefficient ε cell for p = 1 bar under the STP conditions (U0 tn = 1.48 V and U 0 rev = 1.23 V) up to Ucell = 2.0 V. There is a continuous decrease of ε cell,th vs. Ucell from 1.0 to 0.85 when Ucell = Utn = 1.48 V under STP conditions. Figure 1

A Study of Carbon Emission Driving Factors of a Metal Chemical Enterprise in China Based on the LMDI Model

The chemical industry is a typical high-carbon emitting industry, and achieving the goal of net zero emissions by 2050 is challenging. Therefore, metal chemical enterprises have to explore a special path of low-carbon development. This article conducted a case study on a Chinese metal chemical production enterprise with a processing scale of 28,000 t/year. Starting from the analysis of energy consumption carbon emissions, this article used available statistical data at the enterprise level to build a carbon emission estimation model for the enterprise combining different emission categories. Moreover, we also calculated the carbon emissions and carbon emission intensity of the enterprise from 2014 to 2022. Further quantitative analyses on the impact of production scale, energy efficiency, energy structure, and emission coefficient on carbon increment were also conducted using a logarithmic mean divisia index (LMDI) model. The results showed that the reduction in carbon emissions of the enterprise during the research period was due to the improvement of energy efficiency, while the production scale and energy structure served as important driving factors. Based on the results, this article proposes some policy suggestions on the future direction and focus of the enterprise’s carbon reduction work.

Research and Application of Shallow Geothermal Energy Development and Utilization in Shandong Province.

Shallow geothermal energy reserves are abundant and widely distributed in Shandong Province. Vigorously developing and utilizing shallow geothermal energy will play a significant role in improving energy pressure in Shandong Province. The energy efficiency of ground source heat pumps is closely related to geological and other conditions. However, few studies on geothermal exploitation and utilization have been affected by economic policies. This article will investigate the operation of shallow geothermal engineering in Shandong Province, summarize the current number of operating projects, calculate the engineering annual comprehensive performance coefficient (ACOP), analyze the size characteristics of different cities, and analyze their correlation with economy and policy. Through research, it is found that the number of shallow geothermal energy development and utilization is significantly positively correlated with socioeconomic level and policy orientation, and has a relatively small relationship with ACOP. The research results provide a basis and suggestions for improving and optimizing the energy efficiency coefficient of geothermal heat pumps and promoting the development and utilization of shallow geothermal.

Energy efficiency of an electric boiler with indirect surface resistive heating of the heat carrier

Introduction. The share of energy for heating of households makes up to 80 % of the total energy consumption. Works on increase of energy efficiency of HVAC equipment make the biggest contribution to reduction of manmade impact on the environment. Power-to-Heat technology — electric boilers used for heating with water systems with radiators and low-temperature heating devices of the “warm floor” type. The research of energy efficiency of the wall mounted electric boiler equipped with the heat generator of indirect surface resistive heating of the heat carrier is presented.
 
 Materials and methods. The object of the research is an electric boiler ARDERIA E24, with a nominal capacity of 24 kWh, equipped with a circulation pump, an expansion tank with a volume of 6 L, a group of hydraulic safety and heat carrier recharge. Control of the capacity of the boiler is carried out on semistors with cooling radiators located on the reverse line of the circulation circuit. The boiler is equipped with an electric heat generator with indirect resistor surface heating of the heat carrier.
 
 Results. The studied electric heat generators have high specific volumetric power equal to 9.3 kWh/dm3. The average specific power of tubular electric heaters is 25.1 watts/cm2. The coefficient of energy efficiency of the boiler is 0.986. The hydraulic resistance of the unit is 1.25 meters of water column at a flow rate of 1.0 m3/h.
 
 Conclusions. The application of the electric heat generator design consisting of a cast aluminum block with tubular heating elements placed inside and a spiral coolant circulation pipe showed high energy efficiency with coefficients of 0.98–0.986 in the modulation range of heat output. The heat output modulation factor of the electric boiler is 12 (2–24 kW). The energy intensity of the heat generator design is 9.3 kWh/dm3, which is significantly higher than traditional heat generation units with “wet” heating elements. The boiler’s heat output control system eliminates the possibility of the temperature rising above 88 °C on the inner heating medium circulation pipe surface.