A review of solar collectors and thermal energy storage in solar thermal applications

Thermal applications are drawing increasing attention in the solar energy research field, due to their high performance in energy storage density and energy conversion efficiency. In these applications, solar collectors and thermal energy storage systems are the two core components. This paper focuses on the latest developments and advances in solar thermal applications, providing a review of solar collectors and thermal energy storage systems. Various types of solar collectors are reviewed and discussed, including both non-concentrating collectors (low temperature applications) and concentrating collectors (high temperature applications). These are studied in terms of optical optimisation, heat loss reduction, heat recuperation enhancement and different sun-tracking mechanisms. Various types of thermal energy storage systems are also reviewed and discussed, including sensible heat storage, latent heat storage, chemical storage and cascaded storage. They are studied in terms of design criteria, material selection and different heat transfer enhancement technologies. Last but not least, existing and future solar power stations are overviewed.Peer reviewe

Numerical investigations of heat transfer in phase change materials using non-equilibrium model

Phase change materials (PCMs) are drawing increasing attention of researchers nowadays, and they play a pivotal role in thermal energy storage (TES) used in renewable energy resources applications, since these renewable energy, such as solar energy, wind energy and tidal energy, are intermittent and not available at any time. However, most of PCMs suffer from low thermal conductivities prolonging the charging and discharging processes. Metal foams with relatively high thermal conductivities, are believed to be able to enhance heat transfer performance of PCMs for those applications. In this paper, a two-equation non-thermal equilibrium model has been employed to tackle the phase change heat transfer problem in PCMs composites embedded into metal foams. Numerical results show good agreement with experimental data, and indicate that a better heat transfer performance can be achieved by using the metal foams of smaller pore size and smaller porosity, and heat transfer performance of PCMs can be enhanced by up to 10 times by embedded metal foams into PCMs.Peer reviewe

Exergy optimisation for cascaded thermal storage

Cascaded thermal storage, consisting of multiple Phase Change Materials (PCMs) with different melting temperatures, has been proposed to solve the problem of poor heat transfer caused by unavoidable decrease of temperature differences during heat exchange process. This paper conducts a theoretical study of the overall thermal performance for a cascaded thermal storage system. Both heat transfer rate and exergy efficiency are taken into account. The main findings are: the cascaded arrangement of PCMs enhances the heat transfer rate by up to 30%, whilst it does not always improve the exergy efficiency (-15 to +30%). Enhanced heat transfer and reduced exergy efficiency can both be attributed to the larger temperature differences caused by the cascaded arrangement. A new parameter hex (exergy transfer rate) has been proposed to measure the overall thermal performance. It is defined as the product of heat transfer rate and exergy efficiency, representing the transfer rate of the utilisable thermal energy. The simulation results indicate that the cascaded thermal storage has higher overall thermal performance than the single-staged storage despite of higher exergy efficiency loss.Peer reviewe

Analytical considerations of flow boiling heat transfer in metal-foam filled tubes

Flow boiling in metal-foam filled tube was analytically investigated based on a modified microstructure model, an original boiling heat transfer model and fin analysis for metal foams. Microstructure model of metal foams was established, by which fiber diameter and surface area density were precisely predicted. The heat transfer model for flow boiling in metal foams was based on annular pattern, in which two phase fluid was composed by vapor region in the center of the tube and liquid region near the wall. However, it was assumed that nucleate boiling performed only in the liquid region. Fin analysis and heat transfer network for metal foams were integrated to obtain the convective heat transfer coefficient at interface. The analytical solution was verified by its good agreement with experimental data. The parametric study on heat transfer coefficient and boiling mechanism was also carried out.Peer reviewedFinal Accepted Versio

Crocin from Crocus sativus possesses significant antiproliferation effects on human colorectal cancer cells

Aim: To investigate the anti-proliferative effects of Crocus sativus extract and its major constituent, crocin, on three colorectal cancer cell lines (HCT-116, SW-480, and HT-29). The cell growth inhibition effect was compared to that of non-small cell lung cancer (NSCLC) cells. In addition, Crocus sativus’ effect on non-cancer cells was evaluated. Methods: Using high performance liquid chromatography (HPLC), the purity of crocin and the content of crocin extract were determined. Anti-proliferative effects of Crocus sativus extract and crocin on test cells was evaluated by MTS assay. Results: The purity of crocin was found to be 95.9% and the content of crocin in the extract was 22.9%. Significant concentration-related inhibition effects of the extract on all three colorectal cancer cell lines were observed (P < 0.01). The proliferation was reduced most significantly in HCT-116 cells, to 45.5% at 1.0 mg/ml and to 6.8 % at 3.0 mg/ml. Crocin at 1.0 mM, significantly reduced HCT-116, SW-480, and HT-29 cell proliferation to 2.8%, 52%, and 16.8%, respectively (P < 0.01). Since 3.0 mg/ml Crocus sativus extract contained approximately 0.6 mM crocin, the observed effects suggest that crocin is a major responsible constituent in the extract. Significant anti-proliferative effects were also observed in non-small cell lung cancer cells. However, Crocus sativus extract did not significantly affect the growth of non-cancer young adult mouse colon cells. Conclusion: Data from this study demonstrated that Crocus sativus extract and its major constituent, crocin, significantly inhibited the growth of colorectal cancer cells while not affecting normal cells. Crocus sativus extract should be investigated further as a viable option in the treatment of colorectal cancer.Цель: исследовать антипролиферативный эффект экстракта Crocus sativus и его главного действующего вещества, кроцина, на три клеточные линии колоректального рака человека (HCT-116, SW-480 и HT-29). Эффект ингибирования роста клеток оценивали по отношению к таковому для клеток немелкоклеточного рака легкого (НМРЛ) и немалигнизированных клеток. Методы: для очистки кроцина и составляющих экстракта C. sativus применяли высокоэффективную жидкостную хроматографию (ВЭЖХ). Антипролиферативный эффект экстракта и кроцина по отношению к клеткам оценивали при помощи MTS-теста. Результаты: степень очистки кроцина составляла 95,9%, а содержание кроцина в экстракте –22,9%. Отмечали существенное дозозависимое угнетение пролиферации клеток трех линий экстрактом C. sativus (P < 0.01). Наиболее выраженное снижение пролиферативной активности оотмечали для клеток HCT-116 (дo 45,5 % при 1,0 мг/мл и до 6,8 % при 3,0 мг/мл). Кроцин в концентрации 1,0 мM, значительно ингибирует пролиферацию клеток HCT-116, SW-480 и HT-29 (до 2,8, 52 и 16,8% соответственно, P < 0,01). Поскольку 3,0 мг/мл экстракта C. sativus содержат приблизительно 0,6 мM кроцина, отмеченное действие первого подтверждает тот факт, что кроцин — главное действующее начало экстракта. Также показано существенное антипролиферативное действие по отношению к клеткам НМРЛ. Однако C. sativus не оказывал выраженного действия на рост немалигнизированных клеток толстого кишечника молодых мышей. Выводы: данные представленного исследования показывают, что экстракт Crocus sativus и его главный действующий компонент кроцин значительно ингибируют рост клеточных линий колоректального рака и в то же время не влияют на рост нормальных клеток. В дальнейшем следует изучить возможность применения Crocus sativus для лечения больных колоректальным раком

Direct patterning of periodic semiconductor nanostructures using single-pulse nanosecond laser interference

We demonstrate an effective method for fabricating large area periodic two-dimensional semiconductor nanostructures by means of single-pulse laser interference. Utilizing a pulsed nanosecond laser with a wavelength of 355 nm, precisely ordered square arrays of nanoholes with a periodicity of 300 nm were successfully obtained on UV photoresist and also directly via a resist-free process onto semiconductor wafers. We show improved uniformity using a beam-shaping system consisting of cylindrical lenses with which we can demonstrate highly regular arrays over hundreds of square micrometers. We propose that our novel observation of direct pattern transfer to GaAs is due to local congruent evaporation and subsequent droplet etching of the surface. The results show that single-pulse interference can provide a rapid and highly efficient route for the realization of wide-area periodic nanostructures on semiconductors and potentially on other engineering materials

Narrow ridge waveguide high power single mode 1.3-μm InAs/InGaAs ten-layer quantum dot lasers

Ten-layer InAs/In0.15Ga0.85As quantum dot (QD) laser structures have been grown using molecular beam epitaxy (MBE) on GaAs (001) substrate. Using the pulsed anodic oxidation technique, narrow (2 μm) ridge waveguide (RWG) InAs QD lasers have been fabricated. Under continuous wave operation, the InAs QD laser (2 × 2,000 μm2) delivered total output power of up to 272.6 mW at 10 °C at 1.3 μm. Under pulsed operation, where the device heating is greatly minimized, the InAs QD laser (2 × 2,000 μm2) delivered extremely high output power (both facets) of up to 1.22 W at 20 °C, at high external differential quantum efficiency of 96%. Far field pattern measurement of the 2-μm RWG InAs QD lasers showed single lateral mode operation

Genetic characterisation and cytological identification of a male sterile mutant in maize (Zea mays L.)

Male sterile mutants play an important role in the utilisation of crop heterosis. Male sterile plants were found in S5 generations of maize hybrid ZH2, through continuous sib-mating by using the fertile plants in the same population, we obtained a male sterile sibling population K932MS including sterile plants K932S and a fertile plant K932F. The objective of this study was to clarify the genetic characterisation and abortion characteristics by nucleus and cytoplasm effect analyses, cytoplasm grouping, and cytological observation. The results showed that no difference was found between K932S and K932F in the vegetative growth stage, but K932S had no emerging anther or pollen grains. The segregation ratio of fertile plants to sterile plants was 1:1 in the sibling progenies, while it was 3:1 in self-crossing progenies of K932F. The sterility of K932S could be restored among reciprocal progenies when seven normal inbred lines were used as females respectively. The fertility expression of K932S crossed with 30 testers would be changed in different test-crosses and some backcross progenies. The C-type restorer Zifeng-1 (Rf4Rf4) was able to restore the fertility of K932S, and the specific PCR amplification bands of K932MS were consistent with CMSCMo17. The anther of K932S began abortion at dyad with its tapetum expanded radically and vacuolated: this induced abnormality in the shapes of both dyads and tetrads. The microspore could not develop normally, and then it collapsed and gradually disappeared. Hence, K932MS is a C-type cytoplasmic male sterile mutant with a pollen-free, stable inheritance: it has potential application value for further research