Experimental data on Helically Coiled Oscillating Heat Pipe (HCOHP) design and thermal performance

Experimental and derived data from three Helically Coiled Oscillating Heat Pipes (HCOHPs) charged with ethanol, methanol and deionized water working fluids respectively are presented. The data was obtained from prototypes of the HCOHPs fabricated out of copper and tested under laboratory conditions. The primary data presented covers the HCOHP aspects, charging of the working fluid and temperature measurements from Omega K-type Thermocouples installed on the evaporators, condensers, adiabatic sections, and on the cylindrical copper vessel integrated with it. The derived data covers the HCOHPs performances and thermal contact resistance experienced during laboratory testing. The data on the aspects and charging of the working fluid provides useful information for the validation of design parameters of other heat pipes. The measured temperature data and the derived performance data can used to validate the performance of heat pipes in other studies and to depict performance profiles in standard text and reference books. The nature of the data presented as a whole would be useful for comparative analysis involving heat pipes and other passive heat transfer devices

Multiphase change materials for energy storage application in buildings

Experimental study has been carried out towards the development of a multiphase change material (MCM) by combining two fabricated microencapsulated phase change materials (MEPCM-oct and MEPCM-eic) samples. The study also covered the characterization of the developed samples for their thermal properties. For the purpose of validation the thermal properties of the developed MCM sample were compared with that of the core components. The developed MCM sample achieved a combined energy storage capacity of 186 kJ/kg with two melting temperatures of 23.4oC and 34.5oC. Even though the two melting temperatures of the MCM were slightly reduced by 0.18℃ and 0.48℃ in comparison with the MEPCM-oct and MEPCM-eic respectively, their mean energy storage capacities were in perfect agreement. The study has therefore shown that it is possible to overcome some of the scientific barriers towards the development of multiphase change materials but further investigations are needed to enhance overall thermal response

A numerical and experimental analysis of an integrated TEG-PCM power enhancement system for photovoltaic cells

Solar photovoltaic (PV) cells especially crystal silicon cells have witnessed a soaring installed capacity during past years. Research efforts have been made to increase the PV conversion efficiency and one direction is towards the cooling of PV systems since a higher PV temperature impairs its conversion efficiency. Phase change materials (PCM) capable of storing large amounts of latent heat are found to be effective on cooling PV cells while thermoelectric generators (TEG) which are solid waste heat converters can be used for converting the heat from PV into electricity. Therefore, this research investigates the concept of an integrated thermoelectric PCM system to enhance the PV efficiency. Theoretical investigations found that the TEGs had small power output due to small temperature difference under natural convection conditions. However, PCM was effective on hampering PV temperature increase during heat storage process. This research developed a numerical model for thermal simulations of the integrated system and has been validated by experimental results. The effect of various PCM thicknesses, conductivities and phase change temperatures were evaluated. The simulation results stressed the importance of high PCM conductivity for a thick PCM layer to reduce its insulation effect on the TEG and PV layers. Finally, the best thermal performance for the PV/TEG/PCM system was achieved with a 50 mm thick PCM layer with thermal conductivity of 5 W/m K and a phase change temperature of 40–45 °C. Further optimisation and experimental evaluation are however being recommended towards the establishment of the full technical and scientific boundaries

Selective removal of chromium (VI) from sulphates and other metal anions using an ion-imprinted polymer

A linear copolymer was prepared from 4-vinylpyridine and styrene. An ion-imprinted polymer (IIP) specific for Cr (VI) adsorption was prepared by copolymerisation of the quaternised linear copolymer (quaternised with 1,4-chlorobutane), 2-vinylpyridine functional monomer and ethylene glycol dimethacrylate (EGDMA), as the cross-linking monomer, in the presence of 1,1’-azobis(cyclohexanecarbonitrile) as initiator. Ammonium dichromate and aqueous methanol were used as a template and porogenic solvent, respectively. Leaching of the chromate template from the polymer particles was achieved with successive stirring of the ion-imprinted polymer (IIP) particles in 4 M HNO3 solutions to obtain leached materials, which were then used for selective rebinding of Cr (VI) ions from aqueous solutions. Similarly, the non-imprinted polymer/ control polymer (NIP/CP) material was also prepared under exactly the same conditions as the IIP but without the chromate anion template. Various parameters, such as solution pH, initial concentration, aqueous phase volume, sorbent dosage, contact time and leaching solution volumes, were investigated. Scanning electron microscopy (SEM), Fourier Transform Infrared (FTIR) spectroscopy, BET surface area and pore size analysis were used for the characterisation of IIP (both unleached and leached) and CP materials. Optimal parameters were as follows: solution pH, 3; contact time, 120 min; eluent, 20 mℓ of 0.1 M NaOH; and sorbent amount, 125 mg. Maximum retention capacity of IIP and CP was 37.58 and 25.44 mg∙g-1, respectively. The extraction efficiencies of the IIP and CP were compared using a batch and SPE mode of extraction. In the absence of high concentrations of ions, especially sulphate ions, both CP and IIP demonstrated no differences in binding of Cr (VI), which was almost 100%. However, in the presence of high concentrations of sulphate ions, the selectivity on the CP completely collapsed. The study clearly demonstrates the suitably of the developed IIP for selective extraction of Cr (VI) in complex samples such as those from acid mine drainage. The selectivity was also compared by direct injection of the real-world sample, both spiked and non-spiked, into that obtained after IIP selective extraction. Despite the method’s very low detection limits for direct injection (below 1 μg∙ℓ-1), no Cr (VI) was obtained. However, after IIP selective extraction, spiked Cr (VI) was detected in the spiked sample

Simulating the influence of microclimatic design on mitigating the urban heat island effect in the Hangzhou metropolitan area of China

There are many indications that Urban Heat Island (UHI) is a significant contributor to the increased emission of greenhouse gases due to the increase in energy consumption for cooling during summer. Hangzhou is currently the second hottest city in China, and this paper investigates how the West Lake and the Xixi Wetland areas in the city act as passive thermal comfort systems in improving the outdoor built environment and mitigating UHI effect. Through using ENVI-met, this research evaluates the most effective development scenarios of West Lake and Xixi Wetland area for reliving UHI effect. The energy consumptions for cooling in a typical office building located close to the West Lake and Xixi Wetland under different development scenarios of these two ecological resources are then also compared. It was shown that the average atmosphere temperature and urban heat intensity in urban area increased by more than 0.5°C if the West Lake and Xixi Wetland are both transformed to building construction areas. Moreover, the cooling demand of a typical office building in summer would increase by 10.8% due to ambient temperature increasing by 0.5°C

Osteomyelitis of the frontal bone

Osteomyelitis of the skull is a rare clinical presentation. It usually occurs as a complication of trauma or sinusitis. Its complications can be lifethreatening though the initial symptoms and signs are subtle. Early diagnosis and appropriate management to prevent CNS complications reduce morbidity and mortality significantly. Intracranial complications of sinusitis, focal infections and meningitis remain a great challenge. Mortality from complications is 20-40%. The prevalence of skull osteomyelitis is about 1.5% of all osteomyelitis

Experimental investigations into the adsorption enhancement in packed beds using Z-Annular flow configuration

Annular packed bed structures have the potential to overcome limitations of conventional fully packed bed types by offering radial distribution of airflow within them to enhance fluid-solid contact during adsorption and also to minimize pressure drops. In this paper, Z-annular flow configuration is experimentally investigated to evaluate its potential to enhance adsorption. Three typical diametrical ratios (Do/Di) corresponding to 2, 2.35 and 3.08, inferred from literature were used to investigate the adsorption performance of the Z-annular flow arrangement and compared with adsorption performance of a conventionally configured fully packed bed system of similar dimensions.The results showed the Z-annular flow configurations did perform better by achieving bed temperature reductions averaging between 4.22 and 5.47 °C than conventional configuration types. Pressure drops were however observed to be relatively higher in the Z-annular flow configuration bed types than the conventional fully packed bed type due to the endplate in the Z-annular flow configuration impeding the airflow and subsequently causing flow reversal. Overall, the Z-annular flow configuration was found to have the potential to enhance the adsorption capacity of packed beds however further investigation on optimum parameters for this enhancement may be required

Printable microscale interfaces for long-term peripheral nerve mapping and precision control

The nascent field of bioelectronic medicine seeks to decode and modulate peripheral nervous system signals to obtain therapeutic control of targeted end organs and effectors. Current approaches rely heavily on electrode-based devices, but size scalability, material and microfabrication challenges, limited surgical accessibility, and the biomechanically dynamic implantation environment are significant impediments to developing and deploying advanced peripheral interfacing technologies. Here, we present a microscale implantable device – the nanoclip – for chronic interfacing with fine peripheral nerves in small animal models that begins to meet these constraints. We demonstrate the capability to make stable, high-resolution recordings of behaviorally-linked nerve activity over multi-week timescales. In addition, we show that multi-channel, current-steering-based stimulation can achieve a high degree of functionally-relevant modulatory specificity within the small scale of the device. These results highlight the potential of new microscale design and fabrication techniques for the realization of viable implantable devices for long-term peripheral interfacing.https://www.biorxiv.org/node/801468.fullFirst author draf

Experimental Investigation into the Integration of Solid Desiccant Packed Beds with Oscillating Heat Pipes for Energy Efficient Isothermal Adsorption Processes

The heat of adsorption released during physical adsorption of water vapour on solid desiccants increases its surface vapour pressure consequently decreasing its adsorption capacity. In packed beds, this raises the bed temperature subsequently increasing the cooling load and energy required for the regeneration of the solid desiccants. In this study, we experimentally investigate helically coiled oscillating heat pipes (HCOHPs) using ethanol, methanol and deionized water respectively as working fluids integrated with packed beds of varying configurations towards isothermal adsorption. The results show average bed temperature reduction varied with heat output from the bed and the thermal performance of the HCOHPs. The fully packed bed (FPB) integrated with the ethanol HCOHP (EOHP) achieved maximum average bed temperature reduction of 14.0°C. The annulus packed bed (APB) integrated with the water HCOHP (WOHP) achieved a temperature drop of 10.1°C. Adsorption peak temperature reductions on the other hand were strongly dependent on HCOHP start-up. Maximum adsorption peak temperature reduction of 20.8°C in Mass Transfer Zone (MTZ) 1 was attained by the FPB-EOHP integrated system. For the APB, maximum adsorption peak temperature reduction of 13.2°C in MTZ 3 was recorded for Small APB (SAPB)-Methanol HCOHP (MOHP) integrated system. Adsorption rates in the FPB were influenced by the mal-distribution of flow within the bed and increased slightly on integration with the HCOHPs. Maximum rates of 1.47×10-06 kg/s was achieved by the FPB-EOHP. For the APB, the SAPB-WOHP achieved maximum adsorption rates of 1.21×10-05 kg/s. The adsorption rates in the Medium APB (MAPB) on the other hand did not appear to be influenced on integration with the HCOHPs. Overall, performances of the integrated systems were found to be influenced partly by the packed bed configuration, the HCOHPs' performance and the heat transfer resistance between the evaporators and the vessel walls. We recommend further optimization of the system parameters and investigation of its regeneration potential for future practical applications

Sorption of toxic metal ions in aqueous environment using electrospun polystyrene fibres incorporating diazole ligands

Electrospun polystyrene fibres incorporating potassium salts of pyrazole-1-carbodithioate and imidazole-1-carbodithioate were employed as sorbents for heavy metals from aqueous environments. The equilibrating time, initial metal concentrations and sorbent mass for optimal adsorption were 40 min, 5 mg/ℓ and 8 mg, respectively. The optimal pH for metal ion uptake was between 6.3 and 9.0 and was found to be dependent on the basicity of the ligands. Protonation constants for the ligands in aqueous solutions were determined potentiometrically; pK of the imidazole was 6.82 while that of the pyrazole was 3.36. The efficiencies of adsorption and desorption of metals on the imidazolyl-incorporated sorbents were more than 95%, up to the fifth cycle of usage. The limits of quantification were ≤ 0.0145 mg/ℓ for all the metals. Accuracy of the determinations, expressed as relative error between the certified and observed values of certified reference groundwater samples was ≤ 0.2% with relative standard deviations < 3%. Electrospun polystyrene fibres incorporating imidazoles proved to be efficient sorbents for divalent heavy metal ions in aqueous environments as their efficiencies exceeded those of chitosan microspheres, ion-imprinted composites, amino-functionalised mesoporous materials and most of the biomass-based sorbents previously reported on.Keywords: electrospinning, polystyrene, heavy metals, diazol