Experimental investigation of a latent heat thermal energy storage unit encapsulated with molten salt/metal foam composite seeded with nanoparticles

Molten salt has been widely used in latent heat thermal energy storage(LHTES)system,which can be incorporated into hybrid photovoltaic/thermal solar system to accommodate the built environment.Solar salt(60 wt.%NaNO 3 and 40 wt.%KNO 3)was employed as the phase change materials(PCMs)in this study,and both aluminum oxide(Al_(2)O_(3))nanopowder and metal foam were used to improve the properties of pure solar salt.The synthesis of the salt/metal foam composites seeded with Al_(2)O_(3)nanopowder were performed with the two-step and impregnation methods,and the composite PCMs were characterized morphologically and thermally.Then pure solar salt,the salt/2 wt.%Al_(2)O_(3)nanopowder and salt/copper foam composite seeded with 2 wt.%Al_(2)O_(3)nanopowder were encapsulated in a pilot test rig,respectively,where a heater of 380.0 W was located in the center of the LHTES unit.The charging and discharging processes of the LHTES unit were conducted extensively,whereas the heating temperatures were controlled at 240℃,260℃and 280℃respectively.Temperature evolutions at radial,angular and axial positions were recorded,and the time-durations and volumetric mean powers during the charging and discharging processes were obtained and calculated subsequently.The results show that physical bonding between Al_(2)O_(3)nanopowder and nitrate molecule has been formed from the morphological pictures together with XRD and FTIR curves.Slight changes are found between the melting/freezing phase change temperatures of the salt/metal foam composites seeded with Al_(2)O_(3)nanopowder and those of pure solar salt,and the specific heats of the salt/Al_(2)O_(3)nanopowder composite slightly increase with the addition of Al_(2)O_(3)nanopowder.The time-duration of the charging process for the salt/copper foam composite seeded with Al_(2)O_(3)nanopowder at the heating temperature of 240℃can be reduced by about 74.0%,compared to that of pure solar salt,indicating that the heat transfer characteristics of the LHTES unit encapsulated with the salt/copper foam composite seeded with Al_(2)O_(3)nanopowder can be enhanced significantly.Consequently,the mean volumetric powers of the charging process were distinctly enhanced,e.g.,the volumetric mean power of heat storage can reach 110.76 kW/m 3,compared to 31.94 kW/m 3 of pure solar salt.However,the additive has little effect on the volumetric mean power of heat retrieval because of the domination of natural air cooling.

Synthetic biology in the UK-An outline of plans and progress

Synthetic biology is capable of delivering new solutions to key challenges spanning the bioeconomy,both nationally and internationally.Recognising this significant potential and the associated need to facilitate its translation and commercialisation the UK government commissioned the production of a national Synthetic Biology Roadmap in 2011,and subsequently provided crucial support to assist its implementation.Critical infrastructural investments have been made,and important strides made towards the development of an effectively connected community of practitioners and interest groups.A number of Synthetic Biology Research Centres,DNA Synthesis Foundries,a Centre for Doctoral Training,and an Innovation Knowledge Centre have been established,creating a nationally distributed and integrated network of complementary facilities and expertise.The UK Synthetic Biology Leadership Council published a UK Synthetic Biology Strategic Plan in 2016,increasing focus on the processes of translation and commercialisation.Over 50 start-ups,SMEs and larger companies are actively engaged in synthetic biology in the UK,and inward investments are starting to flow.Together these initiatives provide an important foundation for stimulating innovation,actively contributing to international research and development partnerships,and helping deliver useful benefits from synthetic biology in response to local and global needs and challenges.

Broadband THz absorption spectrometer based on excitonic nonlinear optical effects

A broadly tunable THz source is realized via difference frequency generation,in which an enhancement to χ^((3)) that is obtained via resonant excitation of III–V semiconductor quantum well excitons is utilized.The symmetry of the quantum wells(QWs)is broken by utilizing the built-in electric-field across a p-i-n junction to produce effectiveχ(2)processes,which are derived from the high χ^((3)).This χ^((2)) media exhibits an onset of nonlinear processes at~4Wcm−2,thereby enabling area(and,hence,power)scaling of the THz emitter.Phase matching is realized laterally through normal incidence excitation.Using two collimated 130mW continuous wave(CW)semiconductor lasers with ~1-mm beam diameters,we realize monochromatic THz emission that is tunable from 0.75 to 3 THz and demonstrate the possibility that this may span 0.2-6 THz with linewidths of ~20 GHz and efficiencies of ~1×10^(-5),thereby realizing ~800 nW of THz power.Then,transmission spectroscopy of atmospheric features is demonstrated,thereby opening the way for compact,low-cost,swept-wavelength THz spectroscopy.