Background
The purpose of this research is to address ongoing device shortfalls for pediatric patients by developing a novel pediatric hybrid total artificial heart (TAH). The valveless ...magnetically‐levitated MCS device (Dragon Heart) has only two moving parts, integrates an axial and centrifugal blood pump into a single device, and will occupy a compact footprint within the chest for the pediatric patient population.
Methods
Prior work on the Dragon Heart focused on the development of pump designs to achieve hemodynamic requirements. The impeller of these pumps was shaft‐driven and thus could not be integrated for testing. The presented research leverages an existing magnetically levitated axial flow pump and focuses on centrifugal pump development. Using the axial pump diameter as a geometric constraint, a shaftless, magnetically supported centrifugal pump was designed for placement circumferentially around the axial pump domain. The new design process included the computational analysis of more than 50 potential centrifugal impeller geometries. The resulting centrifugal pump designs were prototyped and tested for levitation and no‐load rotation, followed by in vitro testing using a blood analog. To meet physiologic demands, target performance goals were pressure rises exceeding 90 mm Hg for flow rates of 1–5 L/min with operating speeds of less than 5000 RPM.
Results
Three puck‐shaped, channel impellers for the centrifugal blood pump were selected based on achieving performance and space requirements for magnetic integration. A quasi‐steady flow analysis revealed that the impeller rotational position led to a pulsatile component in the pressure generation. After prototyping, the centrifugal prototypes (3, 4, and 5 channeled designs) demonstrated levitation and no‐load rotation. Hydraulic experiments established pressure generation capabilities beyond target requirements. The pressure‐flow performance of the prototypes followed expected trends with a dependence on rotational speed. Pulsatile blood flow was observed without pump‐speed modulation due to rotating channel passage frequency.
Conclusion
The results are promising in the advancement of this pediatric TAH. The channeled impeller design creates pressure‐flow curves that are decoupled from the flow rate, a benefit that could reduce the required controller inputs and improve treatment of hypertensive patients.
This work represents the first time the two (axial and centrifugal) pumps in the Dragon Heart Pediatric TAH have been integrated and tested, utilizing an existing axial flow pump. Development work focused on the centrifugal pump suspension and drive. A new channeled impeller design was realized that met the required performance metrics and yielded flat pressure‐flow curves.
Abstract
Because the variable characteristics of axial piston variable pump can be applied to different working conditions, this paper simulates the actual working conditions of axial piston pump in ...excavator, theoretically analyzes its variable working principle, and focuses on how to adjust the difference between pump outlet pressure and load sensitive port pressure stably. Finally, an axial piston pump variable characteristic test system is built based on LabVIEW software, and a field verification test is conducted, and an effective and reasonable test scheme is selected through analysis and comparison, which provides a certain engineering reference value for the variable characteristic test of axial piston pump.
Abstract
In this article, the formation of highly mineralized water-oil emulsions in Uzbekistan, the complexity of their composition, and the effect of their physical and chemical properties on the ...operation of centrifugal electric pumps used for the extraction and transfer of this type of oil are described. As the period of use of wells increases, the degree of hydration of the well product also increases, which, in turn, complicates the work of centrifugal electric pumps.
Cl
-pump rhodopsin is the second discovered microbial rhodopsin. Although its physiological role has not been fully clarified, its functional mechanism has been studied as a model for anion ...transporters. After the success of neural activation by channel rhodopsin, the first Cl
-pump halorhodopsin (HR) had become widely used as a neural silencer. The emergence of artificial and natural anion channel rhodopsins lowered the importance of HRs. However, the longer absorption maxima of approximately 585-600 nm for HRs are still advantageous for applications in mammalian brains and collaborations with neural activators possessing shorter absorption maxima. In this chapter, the variation and functional mechanisms of Cl
pumps are summarized. After the discovery of HR, Cl
-pump rhodopsins were confined to only extremely halophilic haloarchaea. However, after 2014, two Cl
-pump groups were newly discovered in marine and terrestrial bacteria. These Cl
pumps are phylogenetically distinct from HRs and have unique characteristics. In particular, the most recently identified Cl
pump has close similarity with the H
pump bacteriorhodopsin and was converted into the H
pump by a single amino acid replacement.
•Humidification dehumidification desalination system powered by a heat-pump.•Mathematical models based on mass and energy balance for combined system.•A closed-air open-water water-heated, and ...modified air-heated cycles are analyzed.•Maximum GOR of 8.88 were achieved at 80% effectiveness for air heated and water heated cycles.•A maximum GOR greater than 10 can be reached for ideal components.
Humidification-dehumidification is a carrier gas based thermal technique that is ideal for small-scale water desalination applications. One advantage of humidification-dehumidification systems is the ability to utilize low grade and renewable energies as heat source to drive the system. This work presents theoretical investigation of humidification-dehumidification desalination system operated by a heat pump. The model is based on the first law of thermodynamics, describing heat and mass transfer in the combined humidification-dehumidification-heat pump cycle. The model predicts the performance of closed-air open-water water-heated, and modified air-heated cycle coupled with a heat pump. To improve the Gain output ratio and energy recovery of the system, a heat pump is used as the source of heating and cooling for the humidification-dehumidification desalination system. Energy rejected in the condenser is used as a source of heat in the humidifier whereas the cooling effect of the evaporator is used to cool incoming seawater for effective condensation of humid air in the dehumidifier. A parametric study is conducted to investigate the influence of system operating parameters, including water and air flowrate, seawater temperature, and refrigerant flow rate on the system performance. Results indicate a maximum Gain output ratio of 8.88 and 7.63 obtained at 80% components effectiveness and mass flow rate ratio of 0.63 and 1.3 for modified air heated and water heated cycle, respectively. A maximum gain output ratio greater than 10 can be achieved for humidifier and dehumidifier effectiveness of 100% leading to more energy efficient systems. The cost of desalinated water production is calculated and the effect of major parameters on its variation is also presented.
•A new R744 heat pump system for electric vehicles is proposed in this manuscript.•Experiments have been carried out to study the systems thoroughly.•Comparison of cooling/heating performance of R744 ...and R134a systems is made.•The performance merits of CO2 is re-evaluated.•R744 heat pump system is highly recommended for electric vehicle application.
In this paper, two types of refrigerant, R134a and R744, are studied with different heat pump (HP) structures. Gas cooler, evaporator and indoor gas cooler (IGC) are all micro channel heat exchangers. One four-way valve and a combination of accumulator with internal heat exchanger (ACCU/IHX) are applied in R744 HP system, which can make the heat pump system structure simpler. In addition, one bidirectional throttle valve is applied before the evaporator to obtain the cooling and heating functions for R744 HP system. And the indoor gas cooler and evaporator are in series structure not only for the heating mode but also for the cooling mode in order to increase the heat transfer surface in the R744 system. The system charging test is carried out first to determine the optimal charge amount for the whole system, since it is essential for the stability of the system. Then the R744 and R134a heat pump system cooling and heating performance are studied by the experiment at different ambient working conditions. Test results show that the R744 system proposed in this paper can achieve similar cooling capacity and COP to that of the R134a heat pump. For R744 system, under 40℃ ambient working condition with external air circulation, the cooling capacity can reach 7524 W with COP of 1.36. And the R744 heat pump system can provide higher heating capacity and higher COP than the R134a heat pump system. Especially in the very cold weather, such as the −20℃ and −25℃, the R744 heat pump still can provide enough heating capacity with higher COP. Compared to the traditional R134a heat pump system, the heating capacity of R744 system increases by 83%, reaching 7378 W (R134a, 3994 W) at 6000 revolutions per minute (RPM) under −10℃ ambient temperature conditions. Under −20℃ ambient temperature with external air circulation, the maximum heating capacity is 7502 W with COP of 2.16.
•The application feasibility of the proposed system is analyzed.•The system has advantages in energy saving and environmental protection.•The system will become more competitive in economy with ...governmental subsidy.•The system is a better choice applied in severe cold regions by comparison.
In order to improve the heating performance of conventional air source heat pump system operated in cold regions, an air source heat pump system combined with latent thermal energy storage (ASHPLTES) has been proposed in the previous work. In this paper, a techno-economic analysis of ASHPLTES was carried out in four typical cities of China and compared with quasi-two-stage ASHP (QTASHP) system, coal fired boiler, wall-hanging gas boiler, and direct electric heating. Mathematical models were developed to evaluate the energy, environmental, and economic performances of different heating systems. The results showed that heat pump systems such as QTASHP and ASHPLTES were suitable for space heating due to the advantages of energy saving and environmental protection, although the initial and running cost of heat pump systems was higher than that of conventional heating systems. However, the currently high cost of heat pump systems could be reduced by the increasing productivity and the governmental subsidy. In addition, the static payback period of ASHPLTES compared with QTASHP in Harbin will be cut down to around 6 years if the discount percentage of LTES unit is set as 40%, which indicated that ASHPLTES will be a better choice in severe cold region of China.
•China faces challenges to supply clean building heating services to its citizens.•All building heating solutions have a great potential.•The choice of building heating solutions in China is affected ...by spatial parameters.•It is essential to use spatial analysis to find proper building heating solutions.
With continuing of urbanization, improving of life quality as well as combating against air pollution, China is facing comprehensive challenges to supply modern clean heating to a majority of its citizens. For space heating solutions, currently in urban areas of north China, coal based district heating is prevalent. In urban areas of south China, distributed heating solutions are used. In rural areas, de-centralized coal stoves and biomass stoves are still commonly used. As renewable building heating solution, ground source heat pumps are installed for large scale applications. Building floor areas heated by ground source heat pumps increased tremendously during past ten years. Air source heat pump is being promoted in north Chinese rural areas as part of coal to clean heating project. Solar water heater and electric water heater for domestic hot water supply is widely used in north China and gas water boiler is widely used in south China. A series of policies have encouraged clean fossil fuel district heating in north China. National development plans are also supporting and subsidizing renewable heating technology such as heat pumps. Different building heating technologies have their own advantages and disadvantages from techno-economic and environmental perspectives. The choice of building heating solutions for different geolocations of China is strongly affected by spatial parameters such as local climate condition, population distribution, natural resource availability etc. Therefore, a spatial data analysis method is essential to help stakeholders decide proper building heating solutions in different parts of China by key performance indicators reflecting lower primary energy use, economic affordability and lower environmental impact.
Internal combustion engine (ICE) thermal management is one of the most attractive methods for reducing both fuel consumption and harmful emissions. Conventional ICE cooling uses a dynamic centrifugal ...pump, which is generally designed based on the maximum ICE power. Unfortunately, such devices present significant efficiency reductions when they are operated far from the design point. Therefore, a sliding vane rotating pump (SVRP) has been considered as a substitute for the centrifugal pump because its efficiency is not dependent on the revolution speed and head pressure. This study developed a mathematical model that could be used for designing and simulating an SVRP. Then, an SVRP was built and tested, and the results validated the model under a wide range of operating conditions. Once validated, the model was used as a software platform to improve the SVRP design using a novel approach based on the optimisation of the ports and shape. Moreover, the benefits of this SVRP were assessed by comparing electrical and mechanical actuation using the Worldwide Harmonised Light Vehicles Test Procedure (WLTP). A pump energy reduction of approximately 30% and a CO2 emission reduction of up to 1.4 g/km were obtained.
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•Experimental validated model of Sliding Vane Rotary Pump for engine cooling system.•Development of a novel Sliding Vane Rotary pump model-based optimisation approach.•Improvement of pump efficiency through a new port configuration and machine shaping.•Efficiency benefits and CO2 emission reduction assessment during WLTP driving cycle.•Comparison between variable speed and variable displacement vane pump actuation.
