Varying Flow Rates Research Articles

Operational features of collecting pipelines in the presence of transit and groundwater level slope

The conditions of operation for pressure collecting drainage pipelines in melioration systems that function in the presence of transit flow and groundwater surface levels have been considered. The system of differential equations describing the fluid motion with variable flow rate in the drainage pipe has been analyzed, taking into account the inflow of liquid from the surrounding soil through the side walls in a filtration mode. This system of equations consists of the hydraulic equation of variable mass and a modified filtration equation. The pipeline under study is laid horizontally and operates with a groundwater level slope. A significant complication in the operation of such pipes is the presence of transit flow that enters their initial cross-section and is transported along the entire length of the drainage pipeline. By introducing new variables, the original system is transformed into a dimensionless form. The solution to this system of equations is presented. It is shown that, in this case, the solution to the original system of equations depends on the magnitude of four main factors: the resistance coefficient of the collection drainage pipeline «ζl»; the generalized parameter «A» which comprehensively considers the structural and filtration characteristics of the flow under consideration; the slope of the groundwater level «I»; and the magnitude of the transit flow «Qtr» The analysis employs the concept of an infinitely long horizontal drainage pipeline that operates with a groundwater level slope and transit flow, or, equivalently, a pipeline with infinite filtration capacity of the side wall surfaces. Based on the conducted analysis, relatively simple and convenient analytical expressions have been obtained for calculating the variation of flow rate and head loss along the length of the drainage pipeline operating with transit flow. To simplify the calculations, corresponding auxiliary graphical dependencies have been proposed.

Progress of material degradation: metals and polymers in deep-sea environments

Abstract Given the critical need for ocean exploration, improving the durability of materials in the deep-sea has become a paramount concern. The harshness of deep-sea, such as high pressure, variable seawater flow rates, and corrosive media, lead to premature aging and failure. This work examines the utilization of metals and polymer coatings in deep-sea applications, detailing the characteristics of the deep-sea and its influence on these materials. In particular, chloride ions in seawater pose significant hazards to metal corrosion, which is the main reason for metal failure. Then, the degradation process and the latest research advances of various materials in the deep-sea environment are summarized, and the failure mechanism of the metal/coating system in the deep-sea is analyzed. It was found that the failure of polymer coatings can be divided into three processes, and adding an appropriate amount of fillers to the coating (such as adding 0.2 % graphene to water-based polyurethane) can extend the service life of the coating. Finally, the development trend of the company in the future is predicted. It has guiding and reference significance for the study of the failure behavior of metals and polymers in the deep-sea environment.

Effect of Volumetric Flow Rate on Heat Transfer Characteristics of Single-Fractured Rock with Different Surface Morphology and External Temperature

The primary aim of this study is to explore how varying flow rates impact the heat transfer in single fractures, taking into account the effects of surface roughness, aperture and external temperature of the rock. Utilizing COMSOL Multiphysics, the fluid flow and heat transfer through 3D fracture models characterized by different roughness and apertures were simulated with volumetric flow rates ranging from 1 × 10−6 m3/s to 1 × 10−5 m3/s. The combined effects of these factors on key metrics, including outlet temperature, thermal breakthrough time, energy extraction efficiency, and heat transfer coefficients were systematically analyzed. The results indicate that water flow rate dominantly influences heat transfer, followed by fracture surface morphology and rock external temperature. Higher flow rates enhance both heat transfer and total heat extraction, while also increasing temperature non-uniformity, which improves overall heat extraction efficiency. Surface roughness significantly affects temperature distribution, leading to heterogeneous thermal profiles, especially in narrower fractures. Additionally, higher external temperatures and flow rates facilitate faster thermal breakthroughs by reducing thermal resistance. The interplay between surface roughness and thermal breakthrough time is intricate, with increased roughness prolonging breakthrough times in smaller apertures but potentially reducing them in larger ones. At smaller apertures, increasing the JRC from 2.29 to 17.33 results in a 1.01 to 1.20 times increase in thermal breakthrough time, whereas at larger apertures, thermal breakthrough time decreases by a factor of 1.01 to 1.29. This highlights the importance of carefully selecting fluid parameter in the design of geothermal projects to optimize heat extraction efficiency.

An entropy analysis model and irreversibility assessment of solid oxide fuel cells based on the Gibbs relation of charged particles

Energy conversion is the main purpose of various fuel cells, but the irreversibility of thermodynamic processes – including electrochemical reactions and heat and mass transfer in fuel cells – lead to a decrease in energy efficiency. In this paper, we develop a systemic theoretical model to evaluate the irreversibility of solid oxide fuel cells (SOFCs). By combining the conservation equations for energy, mass, and momentum with the Gibbs relation for charged particles, we establish the energy-balance equation for SOFCs and derive the entropy generation rates (EGRs) associated with electrochemical reactions and charged particle transfer processes. We solve the coupling multiphysics model in a three-dimensional computational unit of a SOFC, and calculate the EGRs and entropy flux rate based on the proposed thermodynamic model and the numerical results. We analyse the conversion and transfer mechanisms of energy based on the distributions of different local EGRs and the entropy flux rate, and the influence of various thermodynamic processes, such as mass transfer, heat transfer, and flow, on the overall operation of SOFCs. The results show that the EGR due to electrochemical reactions in the SOFC is the largest and is mainly due to activation and concentration polarisation. Complex heat and mass transfer processes occur in the corner region formed at the intersection of the channel, the current junction, and the electrode, leading to a higher localised EGR. We also evaluate the effects of variations in the anode gas mass flow rate, the oxygen fraction, and the channel length on thermodynamic efficiency. This study contributes to the understanding of the complex mechanisms of irreversible losses in SOFCs and provides guidance for further improving the thermodynamic efficiency of SOFCs.

Characterization of dynamic interplay among different channels during immiscible displacement in porous media under different flow rates.

Although immiscible displacement in porous media has been extensively studied, a more comprehensive analysis of the underlying dynamic behaviors is still necessary. In this work, we conducted experimental and theoretical analyses on the dynamic interplay among channels during immiscible displacement under varying flow rates. In a rock-structured microfluidic chip, we observed typical displacement patterns, including viscous fingering and capillary fingering, and analyzed their frontiers and efficiencies. Interestingly, we discovered a novel 'V'-shaped recovery rate pattern, which differs from the monotonic curve considered in previous research. The recovery rate reaches its lowest point at an injection rate of 1 μL/min (42%), increasing to 55 and 65% at rates of 16 and 0.1 μL/min, respectively. This increase may attribute to all-directional displacement at lower rates and multi-fingering displacement at higher rates, contrasting with primary fingering displacement observed at intermediate rates. Furthermore, we developed a dual-tube model to investigate the dynamic mechanisms between adjacent channels during the displacement process. At high injection rates, an increase in low-viscosity fluid rapidly reduces overall average viscosity of the channels, accelerating displacement while hindering the displacement process in neighboring channels. Conversely, at low injection rates, increased capillary forces at pore-throat junctions delay breakthrough in one channel, promoting simultaneous displacement in parallel channels and ensuring stability. These findings significantly enhance our understanding of the interplay between viscous and capillary forces in porous media during displacement processes.

Performance of heat sink using graphene nanoplatelets-H2O nanofluids for electronic cooling applications

ABSTRACT This study proposes a novel solution for enhancement of the performance of electronic chips using a liquid channel heat sink with graphene nanoplatelets (GnP) dispersed in deionized (DI) water (H2O). The nanofluid was prepared using a two-step method with variations made in the vol% of GnP from 0.01% to 0.1%, with the addition of sodium deoxycholate (0.75 vol%) added as surfactant. The prepared nanofluids remained stable for two weeks without any sedimentation. The thermo-physical properties at the required temperature have been measured and reported in previously published literature. The nanofluid was passed along the microchannels of the heat sink, and its heat transfer performance was experimentally studied. The heat input to the bottom surface of the heat sink was varied from 60 W to 100 W in increments of 10 W while the variation in the nanofluid mass flow rate was from 0.6 to 2.2 mL/s. The results indicated a 66% decrease in the heat sink base temperature with 0.1 vol% of GnP/H2O nanofluid compared to H2O. The maximum decrease in thermal resistance observed was 58%. The convective heat transfer coefficient was enhanced by 23% higher at 0.1 vol% of GnP/H2O nanofluid compared to H2O.

Soft interface instability and gas flow channeling in low-permeability deformable media

Understanding gas percolation through a clay layer or a shale formation is of great importance for the development of a geologic repository for nuclear waste disposal, a subsurface system for gas storage, and an engineering approach for hydrocarbon extraction from unconventional reservoirs. Gas injection experiments have revealed complex dynamic behaviours of gas percolation through water saturated compacted bentonite, characterized by a high breakthrough pressure, rapid breakthrough, a pressure/stress decay after the breakthrough, a relatively high migration rate, high-frequency periodic/nonperiodic variations in flow rate, stepwise rate reductions during relaxation, and low gas saturation over the whole process, all indicating channelling nature of the processes. Using linear stability analyses, we show that this channelling can autonomously emerge from the instability of the deformable interface between the injected gas and the compacted bentonite matrix driven by local stress concentration, pore dilation, and hydrologic gradient. Channel patterns formed would possess a fractal geometry. We further show that, once a percolating channel is established, the gas injected would percolate through the channel in a chain of gas bubbles, also due to the interface instability, resulting in periodic/chaotic variations in gas flow rate. Our work provides a unified explanation for key features observed for gas percolation in low-permeability deformable media. The work also suggests a possibility of designing an engineered barrier system for a nuclear waste repository that can have controllable gas release while limit water transport.

Improved Prediction of Pump Performance Through the Rotation–Curvature Correction—An Experimental and Numerical Study of a Low-Specific-Speed Helico-Axial Compression Cell in Series

Abstract Within turbomachines, turbulence production and redistribution are affected by system rotation and streamline curvature. However, the most frequently used turbulence models do not account for these effects. In the present paper, we calibrate a rotation–curvature correction to the shear stress transport (SST) turbulence model to improve the accuracy of pump performance predictions through computational fluid dynamics (CFD) for a wide range of relative flow rates. The new formulation was achieved through comparison of experimental and numerical results obtained for a low-specific-speed (nondimensional specific speed ≈ 0.7) helico-axial compression cell in series. CFD results revealed secondary flows and strong rotor–stator interactions. Steady-state simulations with the standard SST turbulence model were unable to accurately predict pump performance because of such inherently unsteady features. Unsteady simulations improved the predicted performance, but the head coefficient was up to 10% higher than test results at part-load operation. Through calibration of a rotation–curvature correction, the error in the predicted head coefficient was essentially eliminated for relative flow rates above 50% relative flow. Below 47% relative flow, a rotating stall-phenomenon was identified. The stall cell propagated at a rate of 0.4 times the impeller angular frequency, and we identified a propagation mechanism related to a circumferential variation in impeller tip leakage flow (TLF) rate. The presented turbulence model formulation can improve performance predictions in turbomachinery applications where leakage flows are significant, and forms a basis for future work on extended modeling of increasingly complex operating conditions.

GMP-Compliant Automated Radiolabeling and Quality Controls of [68Ga]Ga-FAPI-46 for Fibroblast Activation Protein-Targeted PET Imaging in Clinical Settings.

In nuclear medicine, molecular imaging of the tumor microenvironment using radiopharmaceuticals (RPs) targeting cancer-associated fibroblasts is gaining significant interest. Among these RPs, [68Ga]Ga-FAPI-46 for positron emission tomography (PET) imaging is frequently used in clinical research protocols. To ensure that the production of this RP complies with good manufacturing practices, process automation is widely adopted. In this context, an automated method for preparing [68Ga]Ga-FAPI-46 was designed using a GAIA® synthesizer. Additionally, a HPLC method was developed and validated to determine the radiochemical purity (RCP) of [68Ga]Ga-FAPI-46 and ensure product quality. The validated HPLC method showed excellent repeatability, with coefficients of variation (%CV) for RCP and retention time (tR) below 0.03 and 0.16%, respectively, across 10 measurements. The radiochemical identification of [68Ga]Ga-FAPI-46 showed comparable tr values to [natGa]Ga-FAPI-46 (6.65 and 6.59 min, respectively). The limits of detection (LOD) and quantification (LOQ) were 79 and 42 kBq/mL, respectively, with a linear detector response between 62.9 and 0.08 MBq/mL (R2 = 0.9999). The method proved robust, tolerating minor variations in mobile phase flow rate and composition. This validated radio-HPLC method can be used routinely for the quality control of [68Ga]Ga-FAPI-46. Finally, three RP validation batches were produced using the automated method described and subjected to multiple quality controls. All three synthesis products met the expected specifications, notably regarding appearance, chemical and isotope identification, pH, sterility, stability, and radionuclidic and radiochemical purity.

Influence of flow rate and fiber tension on dynamical, mechanical and acoustical parameters in a synthetic larynx model with integrated fibers.

The human voice is generated by the oscillation of the vocal folds induced by exhalation airflow. Consequently, the characteristics of these oscillations and the primary sound signal are controlled by the longitudinal tension of the vocal folds, the flow rate, and their prephonatoric position. To facilitate independent control of these parameters, a synthetic larynx model was developed, as detailed in a previous publication. This study aims to statistically analyze the influence of airflow and fiber tension on phonation characteristics, such as periodicity and symmetry, glottis closure during vocal fold oscillations, as well as tissue elasticity and generated sound. A total of 76 experiments were conducted and statistically analyzed with a systematic variation of flow rate and longitudinal tension within the vocal folds.During these experiments, vocal fold motion, subglottal pressure, and emitted sound were meticulously measured and analyzed. Groupwise statistical testing identified the flow rate as the main influencing parameter on nearly all phonation characteristics. However, the fundamental frequency, stiffness parameters, and quality parameters of the primary sound signal are predominantly controlled by the longitudinal tension within the vocal folds. The results demonstrated a complex interplay between the flow rate and tension, resulting in different characteristics of the produced sound signal.

Electrical characteristics of photovoltaic (PV) solar panel and hybrid PV/thermal (PV/T) solar panel

Solar collectors and photovoltaic (PV) solar panels can convert solar radiation into heat and electrical energy. A hybrid PV/thermal (PV/T) solar panel was tested in this study. The hybrid PV/T solar panel was tested using a spiral absorber and water flow levels range from 0.01 kg/s to 0.03 kg/s. As a result, with variable water flow rates and irradiation intensity of 700 and 900 W/m2, the efficiency of hybrid PV/T solar panels varied. The highest electrical efficiency attained was 4.06% in hybrid PV/T solar panels at 900 W/m2 with 0.025 kg/s of mass flow while 3.65% by PV solar panels. In addition, plotted current-voltage and power-voltage curves were used to show the electrical properties of the solar PV panels and hybrid PV/T solar panels.

DNA-labeled chitosan nanoparticles: A potential new surrogate for assessing rotavirus attenuation and transport in sand filtration water treatment

Despite being a model in waterborne risk assessment, rotavirus attenuation and transport in sand filtration water treatment remains poorly understood due to a lack of representative surrogates. We investigated the suitability of DNA-labeled chitosan nanoparticles (DCNPs) to mimic rotavirus attenuation and transport in coastal and alluvial sands. Chitosan nanoparticles were synthesized and coupled with a DNA tracer. Compared to rotavirus, DCNPs had similar size (79 ± 7.2 nm vs. 72.5 nm) and buoyant density (1.65 ± 0.07 g/cm³ vs. 1.36–1.40 g/cm³) but a less negative zeta potential (−20.61 ± 1.94 mV vs. −29.77 ± 0.86 mV) and lower hydrophobicity (0% vs. 44%). Filtration experiments (flow rate 1.26–1.27 ml/min, pH 6.0, electrical conductivity 224–226 μs/cm) showed that DCNPs approximated rotavirus attenuation in coastal and alluvial sands (p ≥ 0.07). Repeated dosing of rotavirus and DCNPs caused removal efficiencies to decline in the sand media. Both entities displayed faster and less dispersive transport than a nonreactive solute tracer (NaCl) in sand media. This preliminary study suggested that DCNPs can approximately mimic rotavirus attenuation and transport in coastal and alluvial sands. However, further validation under diverse experimental conditions is necessary. This includes varying flow rates, pH levels, ionic strengths, and the presence of multivalent cations (e.g., Ca2+ and Mg2+) and organic matter. DCNPs, made from a nontoxic, biocompatible, and biodegradable natural biopolymer, hold promise as a safe tool for assessing rotavirus attenuation and transport in sand filtration water treatment and aquifer filtration processes.

Dynamic combustion optimization of a pulverized coal boiler considering the wall temperature constraints: A deep reinforcement learning-based framework

Coal-fired power generation boilers are susceptible to low combustion efficiency, pollutant exceedance, and over-temperature tube burst during deep peak shaving due to load fluctuation and mass flow rate variation, which seriously affects unit economics, environmental protection, and safety. In this paper, the issue of boiler combustion optimization under variable load conditions is investigated using a data-driven approach. (1) Based on the published literature, a multi-objective prediction model based on Channel Selection Convolutional Neural Network (CS-CNN) for boiler thermal efficiency, NOx emission and wall temperature was developed, taking into account the safety of the unit under fast variable loads (the range of wall temperature varies widely and is prone to over-temperature). (2) Conventional multi-objective optimization algorithms are time-consuming and hard to satisfy the real-time decision-making of combustion in the furnace. In this research, we developed a combustion decision-making agent based on the Twin Delayed Depth Deterministic Policy Gradient (TD3). By interacting with the predictive model and learning the combustion strategy, the agent has the ability to optimize the unfamiliar operating conditions of the boiler. Simulation experimental tests were carried out on real historical data from a 600 MW down-fired boiler and the results showed that thermal efficiency increased by 0.411 %, and NOx emissions decreased by 17.701 mg/m3, with the safety of the wall temperature maintained. A single decision by the TD3 is almost instantaneous, with an average time of 0.004 s. The decision-making efficiency was much better than the traditional search-based optimization algorithms.

Sim‐Net: Simulation Net for Solving Seepage Equation Under Unsteady Boundary

ABSTRACTThe seepage equation plays a crucial role in fields such as groundwater management, petroleum engineering, and civil engineering. Currently, physical‐informed neural networks (PINNs) have become an effective tool for solving seepage equations. However, practical applications often involve variable flow rates, which pose significant challenges for using neural networks to find solutions. Inspired by Deep Operator Network (DeepONet), this paper proposes a new model named Simulation Net (Sim‐net) to deal with unsteady sources or sinks problems. Sim‐net is designed to simulate and solve seepage equations without the need for retraining. This model integrates potential spatial and temporal features based on spatial pressure distribution and well bottom–hole pressure, respectively, which serve as additional signposts to guide neural networks in approximating seepage equations. Sim‐net exhibits transfer learning capabilities, enabling it to handle variable flow rate problems without retraining for new flow conditions. Numerical experiments demonstrate that the trained model can directly solve seepage equations without the need for retraining, indicating its superior applicability compared to existing PINNs‐based methods. Additionally, in comparison to the DeepONet, Sim‐net achieves higher accuracy.

Study of municipal solid waste treatment using plasma gasification by application of Aspen Plus

Abstract Plasma gasification is a viable and efficient technique for handling solid waste, including hazardous waste, while also holding the potential for energy recovery. The objective of this study is to analyze the treatment of municipal solid waste (MSW) using plasma gasification by application of Aspen Plus software. An earlier proposed model was used to analyze the effect of employing different types of gasifying agents as plasma gas, on the composition of syngas produced. The lower heating value, cold gasification efficiency and carbon conversion efficiency were calculated and compared in each case. A sensitivity analysis study was also carried out to observe the effect of variation in plasma gas flow rate and feed flow rate on the composition of syngas generated. The capital, operational and maintenance costs of the process were determined using existing correlations. For a feed rate of 20,000 kg per hour of MSW, the highest yield of syngas (CO (33.48 %), and H2 (34.30 %) with the highest LHV (7.9 MJ/N-m3)) were produced when air was employed as plasma gas. The cold gas efficiency and the carbon conversion efficiency were at their peak when air was used as the gasifying agent. The sensitivity analysis revealed that as the flow rate of plasma gas increases syngas production decreases while the increase in MSW flow rate results in an increase in syngas production. Additionally, the cost analysis revealed that for a plasma gasification plant that can handle 500 tons of MSW per day, the estimated capital and annual operational and maintenance costs are $125,496,721 and $9,833,892 respectively.

The relationship between land use change and flood flows, a case study in a transboundary watershed

Introduction: Introduction: The HEC-HMS model was applied in the transboundary basin of the Zarumilla River (Ecuador – Peru) to simulate the flows that would occur during maximum precipitation events. Methodology: The model integrated the precipitation determined by intensity equations, the infiltration defined by the curve number, the rain - runoff transformation by unit hydrographs, the hydrological routing calculated by applying Muskingum - Cunge and was calibrated by a frequency analysis using the hydrometric information available. Results: The model was executed satisfactorily and the resulting maximum flows at the outlet of the basin varied between 1.100 m3/s and 1.670 m3/s depending on the return period. A land use scenario for the year 2027 was generated using information from 2014 and 2017 that was evaluated with the model. Discussion: The transitions with the largest area of influence observed were pasture to crop, forest to crop and crop to pasture. Other classifications do not present a significant change. Conclusions: The flows calculated with the coverage of the generated scenario are lower than those calculated for 2017, due to the expansion of crops, which are mostly fruit crops. Despite this, the variation in flow rates was not very significant.

On the influence of the refrigerant inlet position and circuitry layout on plate-finned tube evaporator performance through the hybrid method

Abstract Multiple factors can impact the performance of a plate-finned tube evaporator in terms of heat transfer rate and refrigerant pressure drops, including the circuitry layout and the position of the refrigerant distributors. In order to assist designers, various circuitry layout alternatives together with different refrigerant inlet positions were examined in this work, using the hybrid method to calculate the evaporator performance. Based on prediction functions coming from the outcomes of either numerical, analytical, or experimental analysis, the hybrid method has the advantage of combining affordable computing costs with accurate findings. Moreover, the refrigerant inlet position can cause uneven vapor quality entering the various circuits. This characteristic, along with the variation in flow rates it implies, was also examined to investigate their influence on the heat exchanger’s performance.

Impacts of jet inflow on hydrodynamic performance and waste removal efficiency in recirculating aquaculture system aquaculture tanks based on prototype experiments

Although scaled physical models and numerical simulations have been employed to study the hydrodynamic performance of recirculating aquaculture system (RAS) aquaculture tanks, there remains a paucity of prototype experiments that fully reflect the actual hydrodynamic performance. In this study, a prototype experiment was conducted on RAS aquaculture tanks, utilizing advanced image processing techniques specifically adapted to the prototype scale. This study focused on impacts of various jet inflow parameters, including jet inflow angle (0°, 10°, 20°, 30°, 40°, 45°, 50°, 60°, and 70°), jet inflow rate (150, 180, 210, and 240 l·min−1), jet inflow area (942 and 1884 mm2), and jet inflow location (curved wall and straight wall), on the hydrodynamic performance and waste removal efficiency of RAS aquaculture tanks. The results demonstrated the hydrodynamic performance—specifically average flow velocity, flow field uniformity, and the extent of low-velocity zones conjointly determining waste removal efficiency. The curved wall proved to be the optimal location for inflow pipe placement, while a 45° jet angle yielded the best balance between hydrodynamic performance optimization and waste removal efficiency. Furthermore, reducing the inlet area significantly improved average flow velocity and flow uniformity, whereas variations in inlet flow rate had minimal impact on these factors. Supported by these compelling findings, this study offers theoretical insight and practical guidance for achieving efficient aquaculture in RAS, thereby contributing to the advancement of sustainable aquaculture practices.

Analysis of the Heat Content of Exhaust Gases from a Heavy-Duty Diesel Engine under Real-world Driving Conditions and Cold Start Operation

Abstract European Commission is currently working on defining new Euro 7 standards for light and heavy-duty vehicles, which will set severe restrictions on emissions in real driving conditions, and under cold-start operations. It is well known that about 60% of fuel energy converted in a diesel engine is lost in exhaust flow, coolant, and other forms of loss. A more efficient vehicle usage can be achieved by exploiting such dissipated energy content to produce additional mechanical or electrical energy. Several solutions can be adopted for Waste Heat Recovery (WHR) systems. Among them, exploiting the synergy between Organic Rankine Cycles (ORCs), thermal storage with Phase Change Materials (PCM), and electric hybridization is the solution adopted in the research project IRIDESCENT (biodIesel hybRID Electric buS with waste heat reCovEry aNd sTorage). The efficacy of recovering heat content from exhaust gases in reducing fuel consumption has already been demonstrated under stationary conditions. However, one of the challenges in applying WHRs to the powertrain of road vehicles is the fast dynamics of the engine load that determines fast variations in the flow rate and temperature of the exhaust gases. This makes it difficult to optimize energy recovery and explains the need to adopt PCM thermal storage systems. In this framework, the goal of the present work is to characterize the variability of temperature and flow rate in the exhaust gases of a diesel engine for heavy-duty applications under real-world driving conditions. To this end, a dataset of information retrieved from the scientific literature for the Isuzu FTR850 truck was used. The dataset consists of twenty-eight trips performed with the same driver over the same route. It includes both hot-start and cold-start trips and three different values of trailer load (0, 1500, 3000 kg). For each trip, data from GPS, ambient sensors, onboard diagnostics (OBD) systems, and portable emissions measurement systems are made available with a frequency of 1 Hz. In this investigation, a statistical analysis of the data set and a preliminary selection of the ORC and PCM technologies are performed.

Control of Carbon Dioxide Bivalent Heat Pump on Heating of Buildings. Part II

The control system of a bivalent heat pump (BHP), using as low potential heat (LPH) sources both the heat of the return water of the network and the heat of the outside air, is considered. The aim of the work is to determine the parameters of the thermodynamic cycle of the heat pump, which would ensure the operation of the heat pump at variable temperatures and flow rates of the re-frigerant in the load. The set goal is achieved by solving the following tasks: analysis of the methods of synthesis of systems at variable load, analysis of the operation of the system at random disturb-ances, development of the heat pump automatic control system (ACS). The main result of the work is: the scheme of the heat pump, which can work with variable pressures of the evaporator and the gas cooler, as well as the technical solution, in which the enthalpy difference at the evaporator remains constant regardless of the outside air temperatures Significance of the obtained results consists in crea-tion of the BTN scheme, which allows to provide both qualitative and qualitative-quantitative laws of regulation of thermal regime of a building at increase of SOR of a heat pump, thanks to rational choice of a temperature schedule of regulation. Local storage using electrochemical accumulators at the re-quired capacity would be very expensive and would make the entire installation unprofitable. The only reasonable solution is interaction with the grid, which requires, in addition to the technical means of interfacing, the presence of appropriate regulations governing the transfer of electricity generated by the local facility to the grid, especially if the generation will be carried out throughout the year. Keywords: bivalent heat pump scheme, automatic control, random disturbances, reliability, district heating, carbon dioxide.