Hybrid Ground Vehicle Thermal Management System Using Heat Pipes—Model and Control

The development of Hybrid Electric and Unmanned Ground Vehicles (HEV and UGV) offer various benefits including improved vehicle performance, compatibility with high level control systems, reduced fuel consumption, and less environmental pollution. According to the International Energy Agency (IEA), the number of HEVs and EVs is expected to reach 20 million by the year 2020 (Green Car Congress, 2017). Compared with traditional Internal Combustion (IC) engines, hybrid powertrains are more complicated due to additional electronics including the electric motor, battery pack, and control units. However, these additional components introduce new challenges for the powertrain thermal management system design since they have different operating temperature requirements and modes of heat generation. In a hybrid vehicle, the modes of heat generation, apart from the IC engine, include the electric motor, battery pack, and some electrical subsystems, which lead to a more demanding thermal control system. A traditional vehicle cooling system is composed of a mechanical water pump, radiator fan(s), hoses, and other mechanical actuators such as a thermostat valve. In recent times, however, computer-controlled actuators such as an electric water pump, variable speed fan(s), and smart valve(s) are being used for higher efficiency and performance. This approach, although effective and efficient for the common IC engine, may pose problems when it comes to the hybrid powertrains owing to limited space, different operating conditions, heat generation rates, etc. In this dissertation, several innovative designs, optimizations, and control strategies using heat pipes in the thermal management system targeted to hybrid powertrain applications will be analyzed. First, an integrated electric motor air cooling system based on radial heat pipes was designed and the performance was explored through computer simulations. A reduced order electric motor thermal model was introduced to simulate the motor’s internal temperatures. Heat pipes were modeled based on the vapor flow and heat transfer processes, and also selected as the cooling system thermal bus to efficiently remove heat. Mathematical models for the thermal cradle and heat exchanger were developed to complete the cooling system. A series of simulation tests based on the Urban Assault and Convoy Escort driving cycles were used to test the cooling system performance. Numerical results show that the proposed cooling system saves up to 52.1kJ of energy within a 1,800s simulation in comparison to a traditional liquid cooling design (e.g., 67.8% energy saving). Second, an electric motor liquid hybrid cooling system, for HEV applications, using integrated heat pipes and traditional liquid was designed and simulated. The innovative design features two parallel heat transfer pathways allowing optimal heat removal. Detailed mathematical models were developed for the electric motor, heat pipes, liquid cooling system, and heat exchanger. A classical controller was designed for the heat pipe heat transfer pathway while the liquid cooling pathway was adjusted using a nonlinear controller. Cooling performance was again evaluated based on the Urban Assault driving cycle for various road grades and ambient conditions. Results show that the electric motor temperature can be maintained around the target value of 70°C with 399kJ cooling system energy consumption compared to approximate 770kJ energy consumption with the conventional liquid cooling system (e.g., 48% energy saving). Third, a smart HEV battery pack thermal management system using heat pipes as a thermal bus to remove heat efficiently was developed. The battery cooling system couples a standard air conditioning (AC) system with traditional ambient air ventilation. A lumped parameter battery thermal model was created to predict the battery core and surface temperatures. A nonlinear model predictive controller (NMPC) was developed to maintain the battery core temperature about the reference value. The system performance and power requirements were investigated for various driving cycles and ambient conditions. Results showed that the proposed thermal management system can maintain the battery core temperature within a small range (maximum tracking error of 2.1°C) using a suitable cooling strategy based on the ambient temperature conditions and battery heat generation rate. Furthermore, the system showed the ability to remove up to 1134.8kJ of heat within the 1200s simulation. Fourth, a holistic thermal management system for an Unmanned Autonomous Ground Vehicle (UAGV) with a series hybrid powertrain was developed. The use of heat pipes combined with advanced controllers for the vehicle’s electric motors, battery pack, and engine generator set cooling was examined. A series of mathematical models were developed to describe the dynamics and thermal behavior for these elements. Controllers were designed to maintain the components temperatures about their reference values and minimize energy consumption by regulating multiple actuators (e.g., pump, radiator fan, smart valve, blower, and compressor). A vehicle level simulation was conducted which combines the cooling system power consumption with the vehicle power bus. An Urban Assault driving cycle with various road grades and ambient conditions were used for the simulation to show the robustness of the proposed cooling system. Results show that the component temperatures were maintained around their reference values with small errors (2.1°C) and up to 2,955kJ cooling system energy was saved over the 1,800s simulation using heat pipes and the proposed controllers (e.g., 19.8% energy saving). Overall, this research has developed the basis for the holistic control of HEV powertrain thermal management systems. A suite of model-based advanced controllers was used to simultaneously regulate the cooling actuators for the battery, e-motors, and IC engine. For electronics, heat pipes were introduced to reduce the cooling system energy consumption due to their high effective conductivities. Numerical studies have been conducted using vehicle model under various driving cycle, road grade, and ambient conditions to show the advantages of heat pipes and the proposed controllers. The next generation of thermal management system will feature multiple heat transfer pathways to help reduce energy consumption for a better use of fossil fuel and electric power resources

Artificial disc and vertebra system: a novel motion preservation device for cervical spinal disease after vertebral corpectomy

OBJECTIVE: To determine the range of motion and stability of the human cadaveric cervical spine after the implantation of a novel artificial disc and vertebra system by comparing an intact group and a fusion group. METHODS: Biomechanical tests were conducted on 18 human cadaveric cervical specimens. The range of motion and the stability index range of motion were measured to study the function and stability of the artificial disc and vertebra system of the intact group compared with the fusion group. RESULTS: In all cases, the artificial disc and vertebra system maintained intervertebral motion and reestablished vertebral height at the operative level. After its implantation, there was no significant difference in the range of motion (ROM) of C3-7 in all directions in the non-fusion group compared with the intact group (p>;0.05), but significant differences were detected in flexion, extension and axial rotation compared with the fusion group (

Effect of Nitrogen/Oxygen Substances on the Pyrolysis of Alkane-Rich Gases to Acetylene by Thermal Plasma

It is important to convert alkane-rich gases, such as coke oven gas, to value-added chemicals rather than direct emission or combustion. Abundant nitrogen/oxygen substances are present in the actual alkane-rich gases. However, the research about how they influence the conversion in the pyrolysis process is missing. In this work, a systematic investigation on the effect of various nitrogen/oxygen-containing substances, including N2, CO, and CO2,on the pyrolysis of CH4 to C2H2 was performed by a self-made 50 kW rotating arc thermal plasma reactor, and the pyrolysis of a simulated coke oven gas as a model of alkane-rich mixing gas was conducted as well. It was found that the presence of N2 and CO2 was not conducive to the main reaction of alkane pyrolysis for C2H2, while CO, as a stable equilibrium product, had little effect on the cracking reaction. Consequently, it is suggested that a pretreatment process of removing N2 and CO2 should be present before pyrolysis. Both input power and feed rate had considerable effect on the pyrolysis of the simulated coke oven gas, and a C2H2 selectivity of 91.2% and a yield of 68.3% could be obtained at an input power of 17.9 kW

Optimization of a Nanofiltration Desalination Process for Antarctic Krill Peptides Using Orthogonal Tests

Antarctic krill (Euphausia superba), an important group of marine zooplankton in the Southern Ocean, is the only fishery resource with extremely rich reserves and a low degree of development in the world. Antarctic krill is considered to be the greatest potential source of high-quality marine protein resources due to its abundant biomass and high protein content. Peptides prepared from Antarctic krill exhibit multiple physiological activities, including osteoporosis relief, glucose metabolism regulation, blood pressure amelioration, antioxidation, fatigue alleviation, and anti-aging activity. The production and development of Antarctic krill peptides has recently become an industry focus; however, existing research has been limited to the optimization of enzymatic hydrolysis processes, mainly involving the screening of suitable enzymes and the optimization of enzymatic hydrolysis conditions. Due to the high mineral content of Antarctic krill and the introduction of buffer salt in the process of enzymatic hydrolysis, current Antarctic krill peptides products have a high salt content, which leads to poor sensory experience and health risks. Hence, a process for desalination of Antarctic krill peptides is needed. Desalination methods for bioactive substances include dialysis, ultrafiltration, nanofiltration, electrodialysis, and macroporous resin adsorption. In the field of membrane separation, nanofiltration technology has been widely used in the purification, concentration, and desalination of food components owing to its advantages: low operation cost, no introduction of exogenous substances, no destruction of materials, and low rejection rate of monovalent ions. In order to improve product quality and ensure market expansion, the process of desalination of Antarctic krill peptides using nanofiltration technology was studied and optimized in this study.Defatted Antarctic krill powder was enzymatically hydrolyzed by alkaline protease to obtain Antarctic krill peptides for further use. The main factors affecting the desalination effect of Antarctic krill peptides (peptides concentration, nanofiltration pressure, and cycle times) were optimized by single-factor and orthogonal tests, using the desalination rate and protein loss rate as evaluation indexes. The experimental optimization ranges included peptides concentration of 1%~5%, nanofiltration pressure of 0.6~1.4 MPa and cycle times of 1~5. The salt contents of the samples before and after desalination were quantified using the silver nitrate titration method; the protein contents of the experimental samples were quantified using the Lowry colorimetric method. The quality indexes of the Antarctic krill peptides after treatment (including the basic nutritional composition: moisture content, protein content, ash content, salt content; amino acid composition; and molecular weight distribution) were systematically evaluated by the corresponding national standard methods. All experiments were performed in triplicate, and data were expressed as mean ± standard deviation. Excel 2016, IBM SPSS 20.0, and Origin 2018 were used for data analysis and chart drawing.Single-factor tests revealed that peptides concentration of 3%, nanofiltration pressure of 1.0 MPa and a cycle time of 2 could be selected as the design basis for the L9 (33) orthogonal test. The range value of the orthogonal test indicated that the degree of influence of the three factors on the desalination effect was as follows: peptides concentration > cycle times > nanofiltration pressure. The optimum conditions for desalting Antarctic krill peptides obtained by k value analysis were as follows: peptides concentration of 3.0%, nanofiltration pressure of 1.2 MPa and a cycle time of 3. Under the optimal condition, the desalination rate of the Antarctic krill peptides reached up to (86.35±2.11)%, and the protein loss rate was controlled at (9.10±0.35)%, demonstrating the feasibility of the process. The salt content of the Antarctic krill peptides after desalination was reduced to (1.14±0.12)% and the protein content was (92.73±2.29)%. The molecular weights of the Antarctic krill peptides after desalination were mainly distributed between 189 Da and 6500 Da, of which the proportion of peptides with molecular weight less than 3000 Da was (88.91±2.19)%, conforming to the molecular weight distribution range of bioactive peptides. The amount of essential amino acids in the Antarctic krill peptides after desalination accounted for (40.06±0.10)% of the total amino acids, and the ratio of essential amino acids to nonessential amino acids was (66.82±0.28)%. The amino acid compositions of the Antarctic krill peptides after desalination were ideal and met the standard stipulated by the FAO/WHO. The established nanofiltration desalination process presented good treatment effects, and the obtained peptides were of good quality and high nutritional value.The production of Antarctic krill protein-related products may be the next key development for the processing industry, since the sole high-value products of Antarctic krill at present are Antarctic krill oil and its derivatives. The established nanofiltration desalination process has practical application value and would provide technical support for the development of high-quality Antarctic krill peptides. This research provides scientific support for the efficient utilization of Antarctic krill resources

Cost-Effective Reduced Graphene Oxide-Coated Polyurethane Sponge As a Highly Efficient and Reusable Oil-Absorbent

Reduced graphene oxide coated polyurethane (rGPU) sponges were fabricated by a facile method. The structure and properties of these rGPU sponges were characterized by Fourier transform infrared spectroscopy, thermal gravimetric analysis, X-ray diffraction, and scanning electron microscopy. The rGPU sponges are hydrophobic and oleophilic and show extremely high absorption for organic liquids. For all the organic liquids tested, the absorption capacities were higher than 80 g g^–1 and 160 g g^–1 (the highest value) was achieved for chloroform. In addition, the absorption capacity of the rGPU sponge did not deteriorate after it was reused 50 times, so the rGPU sponge has excellent recyclability

Meta-Analysis Comparing Zero-Profile Spacer and Anterior Plate in Anterior Cervical Fusion

<div><p>Background</p><p>Anterior plate fusion is an effective procedure for the treatment of cervical spinal diseases but is accompanied by a high incidence of postoperative dysphagia. A zero profile (Zero-P) spacer is increasingly being used to reduce postoperative dysphagia and other potential complications associated with surgical intervention. Studies comparing the Zero-P spacer and anterior plate have reported conflicting results.</p><p>Methodology</p><p>A meta-analysis was conducted to compare the safety, efficacy, radiological outcomes and complications associated with the use of a Zero-P spacer versus an anterior plate in anterior cervical spine fusion for the treatment of cervical spinal disease. We comprehensively searched PubMed, Embase, the Cochrane Library and other databases and performed a meta-analysis of all randomized controlled trials (RCTs) and prospective or retrospective comparative studies assessing the two techniques.</p><p>Results</p><p>Ten studies enrolling 719 cervical spondylosis patients were included. The pooled data showed significant differences in the operation time [SMD = –0.58 (95% CI = −0.77 to 0.40, p < 0.01)] and blood loss [SMD = −0.40, 95% CI (−0.59 to –0.21), p < 0.01] between the two groups. Compared to the anterior plate group, the Zero-P group exhibited a significantly improved JOA score and reduced NDI and VAS. However, anterior plate fusion had greater postoperative segmental and cervical Cobb’s angles than the Zero-P group at the last follow-up. The fusion rate in the two groups was similar. More importantly, the Zero-P group had a lower incidence of earlier and later postoperative dysphagia.</p><p>Conclusions</p><p>Compared to anterior plate fusion, Zero-P is a safer and effective procedure, with a similar fusion rate and lower incidence of earlier and later postoperative dysphagia. However, the results of this meta-analysis should be accepted with caution due to the limitations of the study. Further evaluation and large-sample RCTs are required to confirm and update the results of this study.</p></div

Risk ratio (RR) estimate for fusion rate.

<p>Risk ratio (RR) estimate for fusion rate.</p