A Jatropha curcas-based bio-lubricant was developed and evaluated for automotive applications through acid esterification, base-catalyzed transesterification, in-situ peracetic acid epoxidation, and multi-additive blending. The molecular transformations were confirmed by GC–MS and FTIR, and physical properties were assessed using ASTM/ISO methods. Performance was further evaluated through a 12,000 km in-service motorcycle engine test and XRF wear analysis. Transesterification decreased kinematic viscosity at 40 °C from 36.6 to 16.7 cSt, and subsequent epoxidation and additive incorporation increased the viscosity to 47.2 cSt (40 °C) and 15.2 cSt (100 °C), meeting ISO VG-46 requirements. The resultant composition (JOA) showed density (888 kg m⁻³), viscosity index (227), pour point (−20 °C), flash point (230 °C), free fatty acid content (0.1%), and acid value < 0.5 mg KOH g⁻¹. The predominant components of JOA were determined by GC–MS, and ester and epoxide functionalities were confirmed by FTIR. During operation, the viscosity index decreased to 192.9, while maintaining acceptable viscosity retention and thermal stability. XRF analysis indicated controlled wear, with metal concentrations remaining within reported OEM guideline ranges. These results demonstrate the feasibility of using Jatropha curcas oil as a sustainable base stock for automotive lubricants.
In the operational diagnosis of air-source heat pumps, the conventional coefficient of performance faces limitations in distinguishing environmental effects from equipment performance degradation due to its dependency on operating conditions. To address this, this study proposes performance consistency index, based on the second law of thermodynamics. By normalizing the thermodynamic perfectibility under actual operating conditions against its rated value at nameplate conditions, this index establishes an energy efficiency diagnostic method with both operational robustness and design bench-marking capabilities. The study demonstrates that the performance consistency index, inherits the stability and comparability of thermodynamic perfectibility, effectively decouples the impacts of environmental parameter fluctuations and equipment performance degradation, remains independent of operating conditions, and accurately characterizes equipment status. By setting 1 as the design benchmark, deviations between actual performance and design objectives are quantified. Validation through operational diagnosis of four units confirms that the performance consistency index, successfully identifies partial-load energy efficiency degradation and low-temperature performance degradation. The performance consistency index provides a theoretical tool for long-term energy efficiency conservation of air-source heat pumps, enabling precise identification of inefficient units through threshold settings and supporting scientific decision-making for equipment renewal in "coal-to-electricity" projects.
Heating and ventilation. Air conditioning, Low temperature engineering. Cryogenic engineering. Refrigeration
The indoor thermal environment of data centers is based on the supply airflow distribution, which is significantly affected by the geometric configuration of the air-supply system. This study compares four commonly used air supply layouts, namely the cold/hot-aisle airflow open-ended system, hot aisle containment system, cold aisle under racks system, and cold aisle containment system. For each air supply layout, geometric factors such as the plenum height, perforation rate, baffle position, and baffle angles were investigated. Using ANSYS Fluent, up to 288 models of CRAC with different air supply modes and configurations were built. The models were validated using the temperature measurement data at the SmartAisle? cold aisle containment system. The average rack and hot spot temperatures, thermal performance evaluation index, and return temperature index were used as the metrics for comparison. The results show that both increasing the plenum height and decreasing the perforation rate within a certain range contribute to thermal performance improvement. Considering the room temperature profile and evaluation metrics, the overall best performance is achieved in the cold aisle containment case. Finally, the effects of various factors when using \/-shaped and /\-shaped baffles were compared using the models of the cold aisle containment system. The results show that when using \/-shaped and /\-shaped baffles, the optimal perforation rate is 20%, while the optimal static pressure height is 0.5 m and 0.6 m, respectively. Overall, \/-shaped baffles achieve better temperature uniformity than /\-shaped baffles.
Heating and ventilation. Air conditioning, Low temperature engineering. Cryogenic engineering. Refrigeration
Behavior modes, such as self-regulating water supply temperature and switching valves in heating circuits, have significant effects on the energy-saving and comfort of household air-source heat pump floor heating systems. In this study, using an actual residence as an example, the heating characteristics of a household air-source heat pump floor heating system under different water supply temperatures and different numbers of heating circuits were experimentally studied. The indoor air temperature, ground temperature, and system power consumption were measured and recorded. When the average outdoor temperature and the maximum water supply temperature of the unit was -2.3 ℃ and 55 ℃, respectively, the ground temperature was very high and the local dissatisfaction rate of the floor surface temperature was more than 20%. Compared to the water supply temperature of 30 ℃, the power consumption increased by 191% and the temperature difference between the living room and the study area increased by more than 2.5 ℃. When the average outdoor temperature was -1.7 ℃, after closing the corresponding floor heating loop valves in the second bedroom and the guest bedroom, the room temperature of the master bedroom, living room, and the study decreased by 1.4 ℃, 2.9 ℃, and 0.5 ℃, respectively. Also, the power consumption of the system was reduced by 18.7%.
Heating and ventilation. Air conditioning, Low temperature engineering. Cryogenic engineering. Refrigeration
Today, researchers around the globe are looking for suitable alternatives of conventional fillers which can form flexible pavements with satisfactory engineering performance in an environmental friendly and cost-effective manner. This study investigated the engineering, economical, and environmental viability of recycling waste glass powder (GP) and glass-hydrated lime (GL) composite as alternative fillers, in place of stone dust (SD). All fillers were characterized, and asphalt concrete mixes incorporating them at different proportions (4–8.5%) were designed using the Marshall mix design method. The engineering performance of asphalt mixes was analyzed using the static creep analysis, indirect tensile fatigue test, Cantabro test, modified Lottman test, resilient modulus test, mixing time analysis, and boiling water test. Additionally, the design of single km of two-lane flexible pavements utilizing aforesaid mixes was done as per the mechanistically empirical method suggested in IRC 37 guideline. Finally, the economic and environmental analysis was done by comparing their material cost and global warming potential (GWP). GL and GP mixes exhibited better resistance against rutting, fatigue, and low temperature cracking at lower optimum asphalt content than SD mixes. However, GP mixes also displayed poor moisture resistance and adhesion due to the high amount of silica in GP. GL mixes had satisfactory moisture resistance up to 7% filler content due to the fine nature and anti-stripping properties of hydrated lime. The pavement containing GL and GP fillers also reduced material cost and GWP up to 35% while consuming up to 74 tons of GP.
Steam (water vapor) is an important heat carrier with a latent heat value over 2000 kJ kg , which has advantages such as uniform heating, convenient temperature regulation, clean and nontoxic, convenient transportation. Therefore, it has been widely used in industrial production and is mainly provided by industrial boilers. Currently, the research on steam generation mainly focuses on supply energy and efficiency optimization. Fossil fuel, biomass, solar heat, and electric (direct heating) are the input energy source of most boilers. Fossil-fuel boiler is the most widely used boiler in industrial process. The existing boilers are mainly based on the combustion of coal or natural gas. Recently in China, the coal-fired boiler has been restricted to use due to its severe environmental pollution impacts. In this case, natural gas is regarded as a cleaner energy source; however, it is indicated that the gas-fired boilers will also emit gaseous pollutants such as NOX; [3] the high cost of natural gas has increased the cost of production process. Biomass is regarded as carbon-neutral fuel because the CO2 it produced during the combustion process is equal to the amount which was taken from the atmosphere during the growing stage. However, the biomass will also emit PM2.5 and CO during the combustion process, and its resources are not possible to meet the demand for industry heating. Solar heating could also serve as an energy source for steam generation, and current research can be mainly divided into solar heating for industrial processes (SHIP) and small-scale solar-driven steam generation. SHIP with solar collector converts solar irradiation hitting on its surface into thermal energy by heating a suitable heat-transport medium. However, the unavailability at night and the large collector area make this technology difficult for stable industrial steam demand and also the high initial cost may deter the customer. Electricity can be directly used for steam generation in electric boiler, which is quite flexible and easy to use if low-cost electricity is accessible. However, in terms of thermodynamics, electrical boilers have a lower efficiency of its first energy resources (fossil fuel and biomass with efficiency typically between 30% and 50%), whereas electrical-driven heat pump could increase electric heating performance as it absorbs heat from low-temperature heat sources (waste heat, solar heat, or even ambient heat, etc.). There are several heat-pump methods of steam generation appeared to meet the high-temperature industrial steam requirement. Kobe Steel. Ltd. developed two heatpump-based steam supply systems: the high-efficiency steamsupply system with a steam temperature of 120 C and the standard steam-supply system with a steam temperature of 165 C. The heat pump system, which is equipped with a newly developed screw compressor and a high-efficiency motor resistant to high temperatures, uses a refrigerant suitable for high temperature supply. Chamoun et al. proposed a new R718 high-temperature heat-pump system to realize the high temperature output of 145 C. The water vapor heat pump is investigated to satisfy different temperature demands for industrial use with high performance. Wu et al. studied a water vapor high-temperature heat-pump system for waste heat recovery H. Z. Yan, Prof. R. Z. Wang, Dr. S. Du, Dr. B. Hu, Prof. Z. Y. Xu Institution of Refrigeration and Cryogenics MOE Engineering Research Center of Solar Energy Shanghai Jiao Tong University Shanghai 200240, China E-mail: rzwang@sjtu.edu.cn
The healing of bone fractures naturally occurs without surgical intervention. Some damage and fractures in bone tissue are complex and leave remnant deformation, and this requires the use of bone replacement material. Hydroxyapatite (HA) is the main element of the bone mineral form and consider as a bioactive material which supports bone growth. Nevertheless, the HA has poor mechanical properties, such as low tensile strength. Thus the applications in bone replacement have been limited, especially in high load-bearing applications. A Carbone nanotube has newly obtained considerable concern because of their mechanical properties, potentially enhancing the bone implant's clinical efficiency. This study attempted to explain the effect of adding Multi-walled carbon nanotubes MWCNT Nanoparticles to the HDPE/HA bio-composites. Two groups of the composites samples were produced 20HA/80 HDPE and 40 HA/ 60 HDPE with adding (0.6, 1, 1.4, 2) % weights of (MWCNT) to each group. The composites were fabricated using a hot pressing technique with various pressing pressures (29, 57, 86, and 114 Mpa) at a compounding temperature of 150 C° and a holding time of 15 minutes. To evaluate samples' characteristics and performance, X-ray powder diffraction (XRD), surface topography by Field Emission Scanning Electron Microscopy (FE-SEM), tensile strength and, microhardness test were investigated. The results showed that the hybrid bio-composites demonstrated excellent structural integrity, homogeneous with the fibrous structure, and improved mechanical properties. When increasing in MWNT additions and increasing hot-press pressure, enhancing the composites' fracture strength and microhardness is beneficial. The excellent properties of hybrids bio-composite (HA/HDPE/MWCNT) samples for homogeneous fibrous structure and high mechanical properties could be applied in bone tissue engineering for bone reconstruction.
A trial-error procedure is applied for the derivation of correlations to estimate the relative thermal conductivity (kr) and dynamic viscosity (µr) of nanofluids using MATLAB. Thermophysical properties of particles and base fluids, particle diameter (dp), sphericity, capping layer thickness, Brownian motion of a particle, temperature, and volume fraction (φ) are considered. The accuracy of predicting kr and µr of nanofluids is developed using dimensionless parameters involving base fluid and particle characteristics. The results reveal that the estimated values are in a good agreement with the experimental data with a standard deviation of 2.16% and 8.16% for kr and µr of nanofluids, respectively. Besides that, 97.5% of the predicted kr values suit experimental data of kr with a mean deviation of ±5%, whereas 90.4% of the estimated µr values match the data of µr with a mean deviation of ±10%. Therefore, the proposed new equations will be useful for numerical simulation studies and the engineering design of heat transfer devices such as refrigeration systems, solar collectors, and heat exchangers.
Cast glass has great potential for diverse load-bearing, architectural applications; through casting, volumetric glass components can be made that take full advantage of glass’s stated compressive strength. However, the lack of engineering, production and quality control standards for cast glass and the intertwined ambiguities over its mechanical properties-particularly due to the variety in chemical compositions and the lack of understanding of the influence of flaws occurring in the glass bulk-act as an impediment to its wide-spread application. Addressing the above uncertainties, this work studies a total of 64 silicate-based glass specimens, prepared in 20 * 30 * 350 mm beam size, either by kiln-casting at relatively low forming temperatures (970–1120 ∘\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$^{\circ }$$\end{document}C), or by modification of industrially produced glass. For the kiln-casting of the specimens, pure and contaminated recycled cullet are used, either individually or in combination (composite glasses). The defects introduced in the glass specimens during the casting process are identified with digital microscopy and qualitative stress analysis using cross polarized light, and are categorized as stress-inducing, strength-reducing or harmless. The Impulse Excitation Technique is employed to measure the Young’s modulus and internal friction of the different glasses. Differential Scanning Calorimetry is used on a selection of glasses, to investigate changes in the glass transition range and fictive temperature of the kiln-cast glasses due to the slower cooling and prolonged annealing. The four-point bending experiments are shedding light upon the flexural strength and stiffness of the different glasses, while the fractographic analysis pinpoints the most critical defects per glass category. The experiments show the flexural strength of cast glass ranging between 30–73 MPa, according to the level of contamination and the chemical composition. The measured E moduli by both methods are in close agreement, ranging between 60–79 GPa. The comparison of the flexural strength with prior testing of cast glass involving shorter span fixtures showed a decreasing strength with increasing size for the contaminated specimens, but similar strengths for pure compositions. The results highlight the versatile role of defects in determining the glass strength and the complexity that arises in creating statistical prediction models and performing quality control.
A CO2 two-phase thermosyphon loop (TPTL) system in data centers were investigated in this study. The maximum heat transfer capacity, total thermal resistance, and driving temperature difference were compared between CO2 and R22 TPTLs experimentally. The results indicate that under the same filling ratio, the maximum heat transfer capacity of CO2 TPTL was significantly greater than that of R22 TPTL. When the diameters of the riser and downcomer were 9 mm, the maximum heat transfer capacities of the CO2 and R22 TPTLs were 3 300 W and 1 500 W, respectively. When the diameter was 12 mm, the maximum heat transfer capacity of the CO2 and R22 TPTLs were 5 400 W and 2 200 W, respectively. The study also found that the normal working load range of CO2 TPTL was larger than that of R22 TPTL, but the total thermal resistance of CO2 TPTL was lower than that of R22 TPTL. Under different heat transfer capabilities, the driving temperature difference required for CO2 TPTL was 4 °C lower than that of R22 TPTL on average; that is, the cooling source temperature required by CO2 TPTL can be increased by 4 °C under the same conditions. Taking a small data center as an example, it was calculated that the annual energy consumption of the CO2 TPTL system is 7.425 × 105 kW?h lower than that of the R22 TPTL system and 3.182 × 106 kW?h lower than the central air-conditioning system under the climate conditions in Shanghai.
Keywords two-phase thermosyphon loop; CO2; data center; filling ratio
Heating and ventilation. Air conditioning, Low temperature engineering. Cryogenic engineering. Refrigeration
A mechanical vapor recompression (MVR) system is an efficient evaporation system. In this study, the performance of an MVR system in generating high concentration CaCl2 solutions was studied through simulation analysis and experiments. The influence of input parameters, including evaporation pressure and inlet dilute solution concentration, on the regeneration performance of the MVR system was studied. The regeneration rate is affected by evaporation pressure on which the suction density is depended. The higher the evaporation pressure, the higher the regeneration rate and energy consumption of the system. Under the condition that the concentration of the CaCl2 solution at the inlet was 0.3, the SEC value of MVR regeneration system increased from 46.67 to 79.51 kWh/m3, and the COP of the system decreased from 14.4 to 8.2 when the evaporation pressure increased from 20 to 80 kPa. The concentration of the inlet solution affects the regeneration performance of the MVR system by increasing the boiling point of the solution. The higher the concentration of the solution, the higher the boiling point, and the higher the power consumption of the compressor. Under the condition that the evaporation pressure was 20 kPa, the SEC value of the system increased from 36.68 to 75.76 kWh/m3, and the COP of the system decreased from 18.1 to 9.1 when the concentration of inlet CaCl2 solution increased from 0.25 to 0.39. In terms of solution concentration, equivalent moisture content, and evaporation pressure, the CaCl2 solution had the best regeneration performance in the MVR system compared with the LiCl and LiBr solutions.
Heating and ventilation. Air conditioning, Low temperature engineering. Cryogenic engineering. Refrigeration
Aluminium alloys demonstrate exceptional properties such as high strength-weight ratio and corrosion resistance are used for general engineering applications, automobile, automotives and in aerospace industries. However, they suffer some limitations as wear and creep at high temperatures. With the trending developments from nanometallurgy, diverse nano-particle compounds of mono and heterogeneous compositions have been used in reinforcing aluminium and its alloys as widely reported in the public domains. This paper reviews some of the vast literature on the enhancement of nanostructured aluminium alloys and reinforced aluminium nanocomposites. Importance is laid on the tribological and mechanical behaviours of the manufactured composites and nano-composites with respect to their production methods and applications at elevated (high) and cryogenic (low) temperatures. Keywords— Tribology; mechanical behaviours; nanostructure; aluminium alloys; nano-composites; elevated temperatures
Aluminum oxide (Al2O3) and Magnesium-Aluminum oxides (MgAl2O4) are well known refractory materials used in engineering industries. They are built to withstand high temperatures and possess low thermal conductivities for greater energy efficiency. Dross, a product/byproduct of slag generated in aluminum metal production process is normally comprised of these two oxides in addition to aluminum nitride (AlN). Worldwide, thousands of tons of aluminum dross are generated as industrial wastes and are disposed of in landfills causing serious environmental hazard. This paper explores the potential to synergize the characteristics of the favourable contents of aluminum dross and its availability (in tons) via synthesis of refractories and thereby develop a value added product useful for the modern industries. In this work, Al-dross as-received from an aluminum industry which comprised of predominantly Al2O3, MgAl2O4 and AlN, was used to develop the refractories. AlN possesses high thermal conductivity values and therefore was leached out of the dross to protect the performance of the developed refractory. The washed dross was calcined at 700° and 1000°C to facilitate gradual elimination of the undesired phases and finally sintered at 1500°C. The dross refractory pellets were subjected to thermo-physical and structural properties analysis: XRD (structural phase), SEM (Microstructure), EDS (chemical constituents) and thermal shock cycling test by dipping in molten aluminum and exposing to ambient (laboratory). The findings include the favourable prospects of using aluminum dross as refractories in metal casting industries.
Lubricant degradation is the main cause for low performance of the machine such as heavy engineering machines, mining machinery etc. Lubricants are used for smooth running of gears and they also avoid friction and noise. Its performance is affected by high temperature and shearing, due to high temperature viscosity of oil changes and due to shearing its physical property changed or degraded. This paper analyses the failure behaviour of gear oil used in Load Haul Dumper (Model No: Eimco Elecon – 811MK). Gear oil degradation was measured by oil analysis in two sections: (i) fluid properties and (ii) contamination in the oil. Fluid properties were analysed by Viscometer, Rheometer whereas contamination analysis was done by Fourier Transform Infrared spectrometer (FTIR). All tests were performed carefully and their graphs were plotted. Results show that temperature and shearing were two of the several causes for degradation of oil. Viscosity analysis clearly presents that viscosity of oil exponentially decreases with temperature. Viscosity is also decreasing with shear rate at different temperatures. FTIR analysis confirmed that contamination is increasing with continuous use of oil. Temperature and oxidation are the main reasons for degradation. Different composition forming in used gear oil and those were confirmed by infrared spectroscopy absorption table.