Specific Energy Consumption Research Articles

Experimental investigation of the effects of energy ratio and combustion chamber design on engine performance and emissions in a hydrogen-diesel dual-fuel CRDI engine

In compression ignition engines, the use of hydrogen-diesel dual fuel mode has a positive impact on engine performance and emissions. To enhance the impact of hydrogen in dual-fuel mode, it is crucial to properly adjust the energy ratio and design the combustion chamber for dual-fuel mode. This study focuses on these two situations. The study conducted a literature review and designed and manufactured two combustion chambers (Natural Gyration 1, Natural Gyration 2) suitable for dual fuel mode. Using the original combustion chamber and the manufactured combustion chambers, at a constant engine speed of 1850 rpm, at five different loads (3, 4.5, 6, 7.5, and 9 Nm), and at three different hydrogen injection times (1.6, 1.8, and 2.0), tests were performed. Engine performance and emission data obtained as a result of the tests were examined. Tests revealed that at a load of 9 Nm and with a hydrogen energy ratio of 12%, the Natural Gyration 1 combustion chamber increased the internal cylinder maximum pressure by 1.41%, reduced the specific energy consumption by 2.29%, and reduced particulate emissions by 8.82%. On the other hand, it was determined that the Natural Gyration 2 combustion chamber reduced the maximum cylinder internal pressure by 1.98%, increased the specific energy consumption by 2.66%, and soot emissions by 5% at the same load and hydrogen energy ratio.

Experimental study on ammonia-diesel co-combustion in a dual-fuel compression ignition engine

Ammonia, as a carbon-free renewable fuel and a potential hydrogen carrier, is gaining increasing interest in addressing greenhouse gas emissions in industrial applications and transportation. This paper presents experimental studies on the co-combustion of ammonia with diesel fuel in a single-cylinder industrial compression ignition engine operating in dual-fuel mode. The energy share of ammonia ranged from 0 to 60%. Increasing the proportion of ammonia compared to diesel fuel in the compression ignition engine leads to a change in the combustion process character, increasing the kinetic combustion phase at the expense of diffusive combustion. However, it does not result in an increase in the peak pressure rise (PPR) beyond the permissible value of 1 MPa/deg for piston engines. It increases ignition delay and shortens the combustion duration, while also increasing thermal efficiency and decreasing specific energy consumption. An increase in the NH3 share results in a decrease in combustion efficiency, a reduction in unit emissions of NO, CO2, and soot, and an increase in CO emissions. Beyond 42% ammonia share, it reduces unit THC emissions. At a 42% ammonia share, the dual-fuel engine achieves the highest indicated thermal efficiency (ITE), lowest specific energy consumption (SEC), shortest combustion duration, and lowest unit soot emissions.

On Comparing Packed Beds and Monoliths for CO2 Capture from Air Through Experiments, Theory, and Modeling.

This study compares the performance of amine-functionalized γ-alumina sorbents in the form of 3 mm γ-alumina pellets and of a γ-alumina wash-coated monolith for CO2 capture for direct air capture (DAC). Breakthrough experiments were conducted on the two contactors to analyze the adsorption kinetics and performance for different gas feeds. A constant pattern analysis revealed dominant mass transfer resistances in the gas film and in the pores, with axial dispersion also observed, particularly at higher concentrations. A 1D, physical model was used to fit the experiments and thus to estimate mass transfer and axial dispersion coefficients, which appear to be consistent with the hypotheses derived from constant pattern analysis. A dual kinetic model to describe mass transfer was found to better describe the tail behavior in the monolith, whereas a pseudo-first-order model was sufficient to describe breakthroughs on packed beds. A substantial two-order magnitude decrease in mass transfer coefficients was noted when reducing the feed concentration from 5.6% to 400 ppm CO2, thus underscoring the significant mass transfer limitations observed in DAC. Comparison between the contactors revealed notably higher mass transfer coefficients in the monolith compared to the packed beds, which are attributed to shorter diffusion lengths and lower equilibrium capacity. While the faster mass transfer coefficients observed in the monolith experiments led to reduced specific energy consumption and increased adsorption productivity compared to the packed bed at 400 ppm, no significant improvement was observed for the same process at the higher concentration of 5.6% CO2 in the feed. This finding highlights the need to tailor the contactor design to the specific gas separation requirements. This research contributes to the understanding and quantification of mass transfer kinetics at DAC concentrations in both packed bed and monolith contactors. It demonstrates the crucial role of the contactor in DAC systems and the importance of optimizing the adsorption step to enhance productivity and DAC performance.

Development of a novel salt processing technology and its performance and economic evaluation: an experimental study

ABSTRACT This study aimed to develop a novel, sustainable, highly efficient, and affordable salt processing technology tailored to local salt producers. Novel technology converts raw solar sea salt into the finest dried salt, which is widely accepted by various industries. Experiments were conducted at a drying temperature of 80°C, with an air velocity of 30 m/s, and a feed rate of 125 kg per hour to evaluate the proposed novel salt processing technology. Performance evaluation was based on product quality parameters (e.g. wet moisture content, sodium chloride (NaCl) percentage, and whiteness) and specific energy consumption. The economic assessment relied on financial analysis and payback period parameters. The results indicated a reduction in salt sample moisture content from 10.37% ± 0.4% to 0.47% ± 0.02%, with NaCl percentage and whiteness of the salt produced at 98.5% ± 0.3% and 81 ± 0.7, respectively. The specific energy consumption for the novel salt processing technology was 0.119 ± 0.07 kWh/kg of the final salt product. Initial investment requirements totalled IDR 275,435,000, with a payback period of 1.66 years. This proposed novel salt processing technology has the potential to generate high-quality dried salt with a production efficiency of 89.5%. Consequently, it could enhance local producer’s businesses, seize opportunities in the national salt market, support rural industrialisation, and be best configured for Indonesia’s local salt producers.

Ohmic baking of gluten free sponge cake: Analysis of technological and quality characteristics

The demand of gluten-free bakery products is worldwide increasing. Simultaneously, ohmic heating is an alternative heating technology that still deserves further research and development. Therefore, the aim of this work was assessing different technological and quality characteristics of gluten free sponge cake baked by ohmic heating. A custom ohmic system was designed and built and different electric field strengths (1500, 2000 and 2500 V/m) were tested. Conventional baking was performed for comparison purposes. The conventional baking time was 24 min, whilst the ohmic heating time ranged from 3.51 min at 2500 V/m to 7.93 min at 1500 V/m. The ohmic system achieved significantly higher energy efficiencies, reaching nearly 60%, compared to only 4.1% for conventional baking. Additionally, specific energy consumption was significantly lower for ohmic heating. Weight loss was higher for ohmically processed samples, showing larger number of pores in their inner spongy structure. Ohmic heating resulted in a larger volume expansion and a cake with lower density. The remaining quality characteristics, such as color, hardness, cohesiveness, and elasticity, were not significantly different. Results demonstrated that ohmic heating is a suitable technology for baking gluten-free sponge cakes and that it is a promising technology for fast industrial baking of such products.

Optimizing the Electrical Discharge Machining Process Parameters of the Nimonic C263 Superalloy: A Sustainable Approach

Engineers continue to be concerned about electrical discharge-machined components’ high energy consumption, machining debris, and poor dimensional precision. The aim of this research is to propose a hybrid neuro-genetic approach to improve the machinability of the electrical discharge machining (EDM) of the Nimonic C263 superalloy. This approach focuses on reducing the energy consumption and negative environmental impacts. The material removal rate (MRR), electrode wear ratio (EWR), specific energy consumption (SEC), surface roughness (Ra), machining debris (db), and circularity (C) are examined as a function of machining parameters such as the voltage (V), pulse on time (Ton), current (I), duty factor (τ), and electrode type. By employing the VIKOR method, all the responses are transformed into a distinctive VIKOR index (VI). Neuro-genetic methods (a hybrid VIKOR-based ANN-GA) can further enhance the best possible result from the VIKOR index. During this step, the hybrid technique (VIKOR-based ANN-GA) is used to estimate an overall improvement of 9.87% in the response, and an experiment is conducted to confirm this condition of optimal machining. This work is competent enough to provide aeroengineers with an energy-efficient, satisfying workplace by lowering the machining costs and increasing productivity.

Milling efficiency and wear behavior of silicon grinding media in autogenous stirred media milling

This study investigates the wear mechanisms and milling efficiency of silicon as grinding media for autogenous stirred media milling. Fresh autogenous grinding media (aGM) showed an exponentially decreasing wear rate first, while becoming constant at longer grinding times. The wear rate of used aGM was constant throughout the whole milling experiment. Shape and size analysis revealed that chipping and abrasion mechanisms dominate the wear behavior. These mechanisms led to spheroidization of the aGM. The grinding media concentration was introduced as measure for the energy transfer from the stirrer to the product particles. This concept was used for weighting the specific energy consumption. Nanoparticles of around 150 nm were obtained with similar weighted specific energy consumptions, while used aGM performed most efficiently due to their spheroidized shape. Finally, spheroidized aGM still consumed more weighted specific energy than conventional grinding media. However, a direct comparison was difficult due to the different material properties of the grinding media.

Performance analysis of methanol fuelled SI engine with boosted intake pressure and LIVC: A thermodynamic simulation and optimization approach

Methanol (CH3OH) is a low-carbon alternative fuel that can be derived through renewable power-to-fuel conversion, offering lower emissions and a higher resistance to knock in SI engines. However, the sole methanol-powered SI engine delivers less brake power. Fuels with a higher calorific value have been blended to solve this problem. However, this may cause overburden with storage, handling, and correct blending (like when methane and hydrogen are blended). To resolve this, this research suggested a novel approach for increasing the power and efficiency of a SI engine using the LIVC (late inlet valve closing) miller cycle and boosted intake pressure under 14 geometrical compression ratio (GCR) with the addition of the start of spark timing (SOI) and equivalency ratio (λ) effects. A quasi-dimensional thermodynamic model (QTDM) was applied to simulate the engine performance with respect to operating variables of 0.6–1.0 λ, 35.50 ––650 aBDC (after Bottom Dead Centre) LIVC timing, 30.00 ––150 bTDC (before Top Dead Centre) SOI Timing and 0.8–1.5 bar intake pressure. After that, design of experiments (DoE) based response surface methodology (RSM) was applied to determine optimum operating setting to maximize power and efficiency and minimize emission and fuel consumption. The results from the RSM illustrate the optimum input parameters to be 0.793 equivalence ratio, 46.900 aBDC-LIVC, 20.750 bTDC-SOI timing, and 1.5 bar intake pressure. Correspondingly, response output performances were found to be 12.36 kW-indicated power (IP), 11.20 kW- brake power (BP), 43.32 % indicated thermal efficiency (ITE), 39.32 % brake thermal efficiency (BTE), 9150.6 kJ/kWh brake specific energy consumption (BSEC), and 0.3 V%- carbon mono oxide (CO), 1247.8 ppm-nitric oxide (NO) emission at exhaust valve opening (EVO). The ANOVA regression models resulted in 95 % accuracy in forecasting output response and composite desirability of optimization of 0.83. Overall, it was found that miller-based LIVC and boosted intake pressure considerably improve the performance of SI engines, and the results projected would be helpful for further study and industry application.

Hybrid and combined electro-oxidation and peroxi-coagulation processes in effective treatment of textile reverse osmosis concentrate

In this study, the treatment of reverse osmosis concentrate from a textile industry by hybrid and combined electrochemical processes was investigated. Firstly, the operating parameters of single electro-oxidation (EO) and peroxi-coagulation (PC) processes were optimized, and then the performances of hybrid EO-PC, PC-EO, and combined EO/PC processes were evaluated in pollutant removal under optimum conditions. Optimum conditions for processes were determined as pH: 5, 22.5 mA/cm2, inter-electrode distance: 3 cm, 120 min. Removal efficiency of chemical oxygen demand (COD) for the optimum conditions of EO, PC, EO-PC, PC-EO, and EO/PC were 78.5 %, 73.0 %, 73.8 %, 82.0 %, and 91.9 %, respectively. Specific energy consumption of EO, PC, EO-PC, PC-EO, and EO/PC processes were 61.9, 74.0, 64.0, 60.9, and 56.8 kWh/kg COD, respectively. The EO/PC process was the most effective and feasible one among applied single, hybrid, and combined processes. With the EO/PC, reverse osmosis concentrate met the receiving environment discharge criteria.

Hybrid reverse multi-stage flash and multi-effect evaporator systems powered by low grade energy for water desalination

Integration of a reversal multistage flash (RVMSF) and multi-effect evaporators (MEE) desalination technologies driven by waste heat source is studied. The warm RVMSF reject brine is used as a sensible heat source for the MEE process. Three different configurations are compared and proved to outperform the standalone MSFRV system. Based on the best hybrid structure, 69 %, 67 %, and 287 % enhancement in the recovery ratio, the specific energy consumption (SEC), and the gain output ratio (GOR), respectively over the standard RVMSF process were observed. However, this was achieved at the expense of a 46 % increase in the specific heat transfer area. The recovery ratio, specific area, SEC, and GOR were found to improve with primary feed temperature, and temperature drop of the sensible heat powering the MEE. However, for a fixed number of effects, the full leverage of the supplied energy is limited causing variable or slow progress of the key performance indicators. Increasing the number of MEE effects had a positive effect on the performance causing proportional growth of the recovery ratio and GOR. A maximum value of 20.2 % for the recovery ratio and 5.7 for the GOR was observed when ten effects were used in the MEE system.

Excess energy recovery from a stand-alone PV system for freshwater production using RO unit: Techno-economic analysis

A techno-economic assessment of electricity and freshwater cogeneration system powered by a standalone solar PV system is investigated under weather conditions of Al-Khobar City, Kingdom of Saudi Arabia. The excess electricity generated by the PV system is used to operate Reverse Osmosis (RO) desalination unit using three alternative storage types: Battery, Water-Tank, and hybrid Battery/Water-Tank storage system. The RO desalination plant is mathematically modeled, and its hourly specific energy consumption is predicted by taking into consideration variations in pressure and temperature for one full year using Engineering Equation Solver (EES) software. Then, a MATLAB code is developed and used to optimize the PV array with the three alternative storage options. A novel indicator called the Shortage of Water Supply Probability (SWSP) is introduced and used to optimize the storage size and to ensure satisfying water demand. Results showed that the lowest levelized cost of water (LCW = 1.874 $/m3) is obtained when operating the RO desalination plant with a hybrid Battery/Water-Tank storage system. However, LCW is 2.892 and 2.647 $/m3 when battery or water-tank storage systems are used, respectively. From an environmental point of view, utilizing renewable energy to run the cogeneration system saved 131 tons/year of CO2 emissions.

Enhanced methanol production from recycled methanotrophic biomass and its effect on the emission and performance characteristics of a four-stroke compression ignition engine

Methanol production was demonstrated through recycling of Methylosinus trichosporium biomass to curtail time and resources incurred towards recurrent biomass generation. Cumulative methanol titer of 3.6 g/L was achieved after three cycles of biomass reutilization. Methanol was recovered from cultivation medium using distillation attaining a maximum purity of 94.74 %. Different blends of methanol (0–20 % v/v) with diesel were evaluated for their suitability as alternate transportation fuel. Physicochemical properties of diesel-methanol blends either improved or exhibited equivalence relative to pure diesel, as control. The blends were investigated for their effect on emission and performance characteristics of four-stroke compression ignition engine under varying engine loads (25, 50, 75 and 100 %). Brake specific emissions of CO, hydrocarbon and H2S decreased with increasing methanol content in the blend, attaining maximum decrements of 38.8–46.5 %, 39.8–60.7 % and 85.4–87.8 %, respectively, with 20 % methanol-containing blend (M20) under varying engine loads. On the other hand, brake specific NOx emission increased by 27.7–34.8 % under the same conditions. Superior performance parameters e.g., brake specific fuel consumption (0.29 kg kW−1h−1), brake specific energy consumption (12.9 MJ kW−1h−1) and brake thermal efficiency (28 %), were achieved using M20, while mechanical efficiency (80.8 %) exhibited equivalence with pure diesel.

Experimental study on the damage and fracture mechanism of deep coal beds impacted by water jets at different temperatures

The development of abundant deep coalbed methane (CBM) resources has attracted significant attention due to their commercial development potential. However, developing such resources presents many challenges due to their generation in complex geological environments governed by high temperatures and stresses. Thus, this work investigated coal fragmentation using water jets at different reservoir temperatures. The results show that compared with room temperature conditions, under water jet impact, the threshold fracturing pressure of high-temperature coal is lower, the rock-breaking volume is larger, and thermal stress leads to intensified dynamic damage. Indeed, when the temperature exceeds 75.0 °C, the coal undergoes volume fragmentation, and the depth of water jet-breaking coal increases by 81.0 %, while the specific energy consumption decreases by 52.4 %. The threshold fracturing pressure rapidly decreases as temperature increases and stabilizes, presenting an exponential trend. When the temperature exceeds 75.0 °C, the threshold fracturing pressure is maintained at around 10.0 MPa and no longer decreases with the temperature increase. In addition, three-dimensional (3D) damage field analysis highlights that the coal breaking mode shifts from a “water wedge” dominated mode to a “water wedge-thermal fracture” mode as temperature increases. Finally, the dynamic fracturing mechanism of coal under high-temperature conditions of water jet impact has been revealed. The research results of this paper provide a theoretical basis for the hydraulic permeability enhancement design of deep coal seams.

Study on the characteristics and kinetics of microwave hot air combined drying of peanut pods

Drying is an important means to maintain the quality of peanut pods and reduce the risk of mildew. Microwave hot air combined drying is renowned for its efficacy, low-energy consumption, and superior processing quality, rendering it suitable for peanut pod drying. However, its efficacy hinges greatly on various parameters. To enhance drying efficiency and quality, the drying kinetics of peanut pods using microwave hot air combined drying equipment were investigated. Varying microwave power (1.2 kW, 2.4 kW, 3.6 kW), hot air temperature (30 °C, 35 °C, 40 °C, 45 °C), air velocity (0.4 m/s, 0.7 m/s, 1 m/s), and microwave radiation time (4 min, 6 min) were examined. Results indicated a decline in drying time, moisture ratio, and drying rate with increasing microwave power, hot air temperature, air velocity, and microwave radiation time. Peroxide and acid values complied with national standards. The Verma model exhibited optimal fitting. At 45 °C, peanut pod moisture diffusion coefficient was 3.022 × 10−9 m2 s−1, specific energy consumption at 30 °C was 5302 kJ/kg, and thermal efficiency was 42.6 %. The synergistic drying of peanut pods by microwave and hot air has a high moisture diffusion coefficient and thermal efficiency. The kinetic and energy analysis of the drying process can furnish some theoretical foundation for subsequent microwave hot air drying and equipment parameter adjustment.

Techno-economic analysis of AMP/PZ solvent for CO2 capture in a biomass CHP plant: towards net negative emissions

Compared to conventional monoethanolamine (MEA), alternative solvents are expected to substantially contribute to reduce the energy demand of post-combustion CO2 capture from flue gases. This study presents a comprehensive techno-economic analysis of a 27 wt% 2-amino-2-methyl-1-propanol (AMP) + 13 wt% piperazine (PZ) aqueous solution for CO2 capture, compared to a 30 wt% MEA solution. The study addresses the retrofit of a carbon capture unit to a biomass-fired combined heat and power (CHP) plant, effectively making it a bioenergy with a carbon capture and storage (BECCS) system. The treated flue gas has a flow rate of 23 tons/hour (t/h) with 11.54 vol% CO2 and a 90% capture rate is aimed for. Aspen Plus V14 was employed for process simulations. Initially, binary interaction parameters for AMP/PZ, AMP/H2O, and PZ/H2O are regressed using vapor-liquid equilibrium (VLE) data, which were retrieved from literature along with reaction kinetics. Validation of parameters from available experimental literature yields an average absolute relative deviation (AARD) of only 5.9%. Afterwards, a process simulation model is developed and validated against experimental data from a reference pilot plant, using a similar AMP/PZ blend, resulting in 5% AARD. Next, a sensitivity analysis optimizes operating conditions, including solvent rate, absorber/stripper packing heights, and stripper pressure, based on regeneration energy impact. Optimized results, compared to MEA, reveal that AMP/PZ reduces the energy consumption from 3.61 to 2.86 GJ/tCO2. The retrofitting of the capture unit onto the selected CHP plant is examined through the development of a dedicated model. Two control strategies are compared to address energy unavailability for supplying the capture unit. The analysis spans 4 months, selected to account for seasonal variations. At nominal capacity, CO2 emissions, rendered negative by biomass combustion and CO2 capture, reach a maximum of −3.4 tCO2/h compared to 0.36 tCO2/h before retrofitting. Depending on the control strategy and CHP plant operating point, the Specific Primary Energy Consumption for CO2 Avoided (SPECCA) ranges from 4.91 MJ/kgCO2 to 1.76 MJ/kgCO2. Finally, an economic comparison based on systematic methodology reveals a 7.87% reduction in capture cost favoring the AMP/PZ blend. Together, these findings highlight AMP/PZ as a highly favorable alternative solvent.

Effect of Hot Air Drying Temperature on Drying Kinetics, Physico-Chemical Properties, and Energy Consumption of Culture Asparagus (Asparagus officinalis L.)

Influences of drying air temperatures on drying time, specific energy consumption as well as product quality of culture asparagus were investigated in hot-air drying. The drying properties of asparagus samples were performed in a laboratory scale convection dryer at three different temperatures. The drying times of asparagus samples were found as 1200, 630 and 510 min for 50, 60 and 70 °C, respectively. In regard to the data obtained, Midilli et al. model is superior to other models to describe drying behavior of asparagus samples. The effective moisture diffusivity values of asparagus samples were calculated between 6.32 ∙ 10−9−1.62 ∙ 10−8 m2/s and the activation energy was estimated as 43.59 kJ/mol. The highest rehydration content and the least total color change were found in asparagus slices dried at 50 °C. Energy consumption values for asparagus samples dried at 50, 60 and 70 °C temperatures were obtained as 10.14, 5.32 and 4.31 kWh, respectively. In terms of energy consumption values, the best efficiency among all drying temperatures was obtained at 70 °C. It has been determined that the specific energy consumption decreased with increasing temperature.

Impact of HPGR operational pressing force and material moisture on energy consumption and crushing product fineness in high-pressure grinding processes

The paper concerns investigations on potential energy savings and breakage effectiveness, resulting from the application of HPGR device into ore mineral processing circuit. A series of laboratory experiments in HPGR for sulphide copper ore was carried out at four values of pressing force in the press and four levels of moisture of the feed material (according to factorial design 42). Fineness analyses on HPGR products were carried out along with a determination of Bond work indices, specific energy consumption, and throughput for each crushing product. Specific mathematical models for Bond work index, energy consumption, productivity, and breakage intensity measured through the yield of finest particle size fraction and specific comminution ratios in relationship to operational pressing force in HPGR and the feed moisture, were calculated. All models appeared to be highly accurate from the statistical point of view and relationships of both pressing force and the moisture appeared significant. The pressing force has generally demonstrated the highest impact on the investigated effects among all analyzed variables, but it depends on the specific model type.

Energy optimization of hydrogen liquefaction process via process knowledge combined with multivariate Coggin's algorithm

Sustainable and cost-effective transportation of hydrogen is one of the major challenges to futuristic hydrogen value chain. Hydrogen, in its produced form, exhibits low energy density and large volume, rendering it highly unsuitable for transportation, particularly over extended distances. Liquefaction is one of the promising approaches to improve hydrogen's energy density and to make it more compact. However, liquefaction is an energy intensive process, raising the cost of transportation. In this study, the specific energy consumption of the hydrogen liquefaction process is aimed to reduce through knowledge-based optimization followed by optimization using the multivariate Coggin's algorithm to improve energy and economic profiles of the process. Design variables, composite curve, exergy, and economic analyses are performed to evaluate and compare the thermodynamic, economic, and environmental feasibility of the optimized process. The results depict a significant reduction (14.3%) in specific energy consumption to 9.40 kW/kgLH2 without increasing process complexity. Further key improvements include a massive drop in refrigerant flowrates (9.2%), annualized cost (m$ 0.15), and annual CO2 emissions (1008.45 tCO2/annum). The largest exergy destruction is observed in CHX-201, reflecting further room for improvement. These results underscore the potential for optimizing hydrogen liquefaction processes to enhance energy efficiency, process economics and environmental impact, providing valuable insights for researchers and industry professionals seeking to advance hydrogen liquefaction technologies. However, challenges remain in the comprehensive evaluation of chemical exergy for ortho- and para-hydrogen and in conducting advanced exergy analyses to further optimize hydrogen liquefaction processes without adding complexity.

ВИЗНАЧЕННЯ ОПТИМАЛЬНИХ ПАРАМЕТРІВ ФІЛЬТРАЦІЙНОГО СУШІННЯ ЯЧМІННОЇ ПИВНОЇ ДРОБИНИ

In this work, the calculation of specific energy consumption for the process of the barley brewer’s spent grain filtration drying was investigated. It has been determined that the lowest total energy consumption for the evaporation of 1 kg of moisture during the filtration drying of barley brewer’s spent grain from the initial moisture content of the material ω1 = 77.88 % (wt.) to the final value ω2 = 10 % (wt.) is 14898.087 kJ/kg H2O or 4.138 kW/kg H2O for the following process parameters: the height of the layer of dried material H = 120 mm, the thermal agent temperature T = 90 °C, the thermal agent velocity v0 = 1.81 m/sec. Determining the optimal process parameters at which the lowest energy costs for drying the material are possible is important for the design of drying equipment.

Assessment of the Potential for Increasing the Energy Efficiency in the Cooling Sector

Cooling supply to ensure the indoor microclimate is becoming more important as global average air temperatures rise. With growing societal demands for higher thermal comfort and increasing individual cooling solutions in the building sector, global energy consumption for cooling is increasing accordingly. Scientific literature and studies estimate that the demand for cooling energy will have a significant impact on global energy demand in the future. In compliance with the European Union goal of achieving climate neutrality by 2050, it is essential to find solutions for reducing energy consumption in the building sector, which is already among the largest energy consumers and greenhouse gas emission producers. Replacing individual cooling solutions with district cooling in urban areas where higher energy density can be reached is one of the solutions for decarbonizing the building sector. To spatially assess the feasibility of district cooling in certain areas, energy demand mapping can be performed. Within this research mapping is carried out using a geographical information system (GIS) tool. The purpose of the mapping is to identify the places in the city of Riga with the highest district cooling potential. Spatial assessment using a GIS tool can be done in different ways – mostly it depends on the available data. The spatial data (buildings) of the cadastral information system and additional detailed information about buildings were obtained from the Latvian open data portal. Information on the type of use of the building, indoor area and the age of building was attached to each building on the map. Then building energy certificate data containing information on specific energy consumption for cooling (kWh/m2 per year) was obtained from the same portal. By processing the data of energy certificates of buildings, excluding outliers, a specific index was obtained for different types of buildings. For the residential sector, the age of the building is also used. Using cadastral data on the indoor area of buildings and the type of building use, the theoretical cooling demand in Riga is calculated and results are quantified and displayed visually. By visualizing the results with the GIS tool, hot spots with the highest cooling energy demand were detected. Results can be further used to calculate the technical and economic justification for the district cooling solutions in specific areas as well as assess the energy efficiency that would be provided by implementation of district cooling solutions.