Numerical Research of a Solar Driven Bubble Pump for Diffusion Absorption Refrigeration Systems

In conventional vapor compression and absorption refrigeration systems, a compressor or a mechanical pump, respectively circulates the refrigerant. Mechanical input, which is required by the compressor or the pump operation, contributes significantly to the noise level and lessens its reliability and portability. In contrast, diffusion absorption refrigeration (DAR) systems are heat-driven and contain no moving parts. Solar-driven diffusion absorption cooling system uses a low-grade heat to produce a cooling effect, and it's specially tuned for remote locations with high levels of solar radiation. This article studies the performance of a DAR system in Ashdod, Israel. Based on existing models in the literature and on experimental measurement of quantities such as the solar irradiance and the air temperature, the cooling capacity and the COP were simulated. Cooling capacity of the DAR system varies between 100 and 140 W, and COP between 0.09 and 0.17.

Advanced control of the cooling system in IC vehicles

The cooling system of internal combustion (IC), electric or fuel cell vehicles is crucial. Not only that it avoids hazards and vehicle fails but it additionally provides the optimal operating temperature improving the reliability of the vehicle and reduced fuel consumption. The great nonlinearities, variable time constants and time delays present in the cooling system’s model offers challenges from a control point of view. This paper provides a control strategy approach that can keep the optimal temperature regardless of the disturbances in the system and uses three control loops for the engine temperature, the temperature difference between engine inflow and outflow, and the temperature of the radiator outflow. The classical mechanical pump and thermostatic valve were replaced with their electrically actuated equivalent for better controllability. The control strategy was tested using realistic driving conditions provided by the New European Driving Cycle (NEDC).

Endovascular treatment of a sacral dural arteriovenous fistula

Spinal dural arteriovenous fistula (SDAVF) is a rare pathological communication between arterial and venous vessels within the spinal dural sheath. Clinical presentation includes progressive spinal cord symptoms including gait difficulty, sensory disturbances, changes in bowel or bladder function, and sexual dysfunction. These fistulas are most often present in the thoracolumbar region. Diagnoses of SDVAFs are commonly missed, possibly due to the low index of suspicion, non-specific symptoms and challenging imaging. In this case report, we describe a rare presentation of a sacral SDAVF which was detected by collective efforts between endovascular neurosurgery and interventional radiology. We outline the diagnostic and imaging challenges we faced to discover the fistula. In particular, mechanical pump injection instead of hand injection during angiography was required to reveal the fistula. Following identification, the fistula was successfully treated endovascularly by using onyx (ethylene vinyl alcohol glue), a less invasive alternative to surgical intervention.

MICROBIOLOGICAL COMPARISON OF THE ORAL AND PUMP METHODS OF INFLATING GOAT CARCASSES

Two methods of inflating goat carcasses prior to dehairing - the oral and the mechanical pump • are compared for efficiency and microbial contamination. The mechanical pump method was found to be two times faster, to have less total bacterial load with no pathogenic organism as seen in the oral method.

A novel approach for using silica nanoparticles in a proppant pack to fixate coal fines

Hydraulic fracturing operations in coal seam gas reservoirs are highly prone to release coal fines. Coal fines inevitably cause mechanical pump failure and permeability damage as a result of their hydrophobicity, aggregation in the system and pore-throat blockage. One approach to affix these coal fines at their source, and to retard generation, is to introduce a nanoparticle-treated proppant pack. Thus, this research explores coal fines retention (known as adsorption) in a proppant pack using nanoparticles. In the study, the electrolytic environment, pH, flow rate, temperature and pressure were kept constant, while the variables were concentration of silica nanoparticles (0–0.1 wt%) and coal fines concentration (0.1–1 wt%). The objective was to identify silica nano-formulations that effectively fixate coal fine dispersions. Subsequently, the coal suspensions flowed through a glass-bead proppant pack treated with and without nanoparticles, and were then analysed via a particle counter. The quantitative results from particle counter analysis showed that the proppant pack with nanoparticle treatment strongly affected the fixation ability of coal fines. The proppant pack without nanoparticle treatment showed up to 30% adsorption and flowed through the proppant untreated, while proppant pack treated with nanoparticles showed up to 74% adsorption; hence, more exceptional affixation ability to the coal fines. Further, the results indicated that the zeta-potential of silica nanoparticles at higher salinity became unstable, i.e. approximately –20 mV; this low value helped the proppant pack treated with nanoparticles to attach coal fines to it. The ability of nanoparticles to adsorb coal fines is due to their highly active surface, and high specific surface area.

CFD-Based Hydraulic Design and Manufacturing of a Multistage Low Specific-Speed Diffuser Pump

A multistage low specific-speed diffuser pump was designed to achieve very good hydraulic performance with a newly designed integrated diffuser, crossover and return guide vane. The diffuser was designed using a continuous crossover design. The design space of this diffuser was limited because of the usage of a mechanical pump design from a similar existing pump. This paper presents the simulation-based design of this new pump and the role that simulation can play in the manufacturing process. A new diffuser has been designed to obtain optimum efficiency and to ensure that the pump will operate most of its time very close its best efficiency point. The new diffuser was designed using an approach where the diffuser vane was stretched to completely cover the area starting just behind the impeller trailing edge towards the eye of the next stage impeller. This means that the diffuser vanes should now convert velocity into pressure, guide the fluid to the next stage impeller eye while reducing the swirl and uniformizing the flow. The shape of the diffuser has been optimized using response surfaces that were created using Computation Fluid Dynamics (CFD). This way, a diffuser with a minimum amount of losses was obtained, due to smooth and gradual area changes of the waterway. The final design incorporating this diffuser was analyzed using steady-state CFD to create the full performance curve. The design was transferred into a real physical product by manufacturing it. The resulting casting of the diffuser component was scanned using a 3D scanner. The 3D model of the scan was used to make a comparison using CFD between the performance of the designed and the manufactured diffuser. This provided understanding in how deviations due to the manufacturing process influence the performance. Finally, the complete pump underwent a performance test and its results closely matched the performance as calculated using CFD.

Design an Equivalent Left Ventricular Assist Device for Medical Equipment Labs

LVAD is a mechanical pump supporting a weak heart function and blood flow. Sometimes, the heart may not recover fast enough to take over the pumping action immediately after surgery, in such patients a temporary support device has been employed to maintain the pumping action until the patient’s own heart recovers. This device can be considered as a temporary alternative before the process of artificial heart transplantation. In this work, a new equivalent Left Ventricular Assist Device (LVAD) is designed and implemented as a simple circuit for medical equipment labs. The presented LVDA consists of a mechanical motor, tubes, a power source, and microcontroller. The output results show the range of readings near the percentage ranges of the left ventricular pumping of the human adult. This work is significant for the biomedical equipment’s lab. The researcher can deal with the function of the important medical devices which are artificial that can record different readings.