The potential for heat pumps in drying and dehumidification systems II: An experimental assessment of the heat pump characteristics of a heat pump dehumidification system using R114

An experimental heat pump dehumidifier is described. Actual coefficients of performance (COP)_A are plotted against the gross temperature lift (T_CO - T_EV) for various bypass ratios and air velocities. Interpolated values of (COP)_A for a specified temperature lift were obtained by fitting each set for various dry bulb temperatures of air leaving the humidifier using a linear equation. These values of (COP)_A are plotted against the linear velocity of the air stream approaching the evaporator at different dry bulb temperatures. The curves show a maximum of (COP)_A at approach velocities in the region of 1·6 ms^?1.     

High voltage repetitive pulsed power generator by using modular multilevel converter

This paper proposes the development of silicon carbide junction field effect transistor-based high-frequency link (HFL) modular multilevel converter (MMC). HFL has been used in conjunction with MMC to achieve higher current density with less foot print, which is the main requirement for exhaust gas treatment. The proposed system has been developed for various scalable ranges such as 6, 8 and 10 modules per arm to generate square wave unipolar/bipolar pulse and exponential decay pulses. These pulses have been generated for 1?kV/cm with 100?µs and 1000?µs and tested. The proposed system has been developed mathematically and simulated in Matlab/Simulink. Thus, obtained results have been verified by conducting an experiment on 3?kV prototype and results are explored.     

Role of physicochemical factors on bacterial attachment in textile fibrous media

One of the possible approaches to remove the Pseudomonas bacteria from surface water by using textile fibrous media has been studied in this article. The attachment of Pseudomonas bacteria inside textile fibrous media was studied using laboratory column experiment which led to the understanding of the physiochemical interaction between textile surface and the bacteria. Colloid‐filtration theory was used to investigate the effects of various physicochemical factors like pH, ionic strength (M) and mass (g) of the porous media on bacterial attachment. The quantitative assessment of bacterial attachment on the textile surface media was carried out by determining the collision efficiency. The physicochemical factors mentioned above were optimized to obtain maximum collision efficiency so as to achieve maximum bacterial attachment on the textile media surface. Bacterial attachment is found to be directly related to the ionic strength of the suspending medium and the mass of the textile media. A significant improvement in collision efficiency is observed when the ionic strength of the suspended medium is increased. Maximum collision efficiency is achieved at high level of ionic strength and medium level of pH with high level of mass of the textile media.     

Hydrated cement: a promising adsorbent for the removal of fluoride from aqueous solution

The present study was carried out to investigate the potential of cement hydrated at various time intervals for the removal of excess F- from aqueous solution by using batch adsorption studies. The influence of different adsorption parameters, viz. effect of adsorbent dose, initial concentration, pH, interfering ions and contact time were studied for their optimization. It was observed that the adsorbent exhibited reasonably significant F- removal over a wide range of pH. The presence of carbonate and bicarbonate ions in aqueous solution were found to affect the F- removal indicating that these anions compete with the sorption of F- on adsorbent. The equilibrium adsorption data were fitted well for both the Freundlich and Langmuir isotherms and the adsorption capacities were calculated. Comparative studies for F- removal in simulated and field water show relatively higher F- removal in simulated water. XRD and SEM patterns of the hydrated cement were recorded to get better insight into the mechanism of adsorption process. From the experimental results, it may be concluded that HC was an efficient and economical adsorbent for F- removal.     

Quantitative and qualitative studies on the bacteriological quality of Indian white shrimp (Penaeus indicus) stored in dry ice

Indian white shrimp (Penaeus indicus) stored in dry ice at the 1:1 ratio were found to be organoleptically suitable for consumption when they were stored for 24 h without reicing. Shrimp stored in water ice at the 1:1 ratio (as control) were acceptable up to 18 h. Shrimp stored in a combination of dry ice and water ice at the ratio of 1:0.2:0.5 were also found to be acceptable up to 24 h. Total bacterial load ranged from 10(6) to 10(9) cfu g(-1), while total psychrophiles ranged from 10(3) to 10(6) cfu g(-1). Total lactics were found in the levels of 10(2)-10(6) cfu g(-1). H(2)S producers were from 10(3) to 10(5) cfu g(-1). Lowest temperature of -4.8 degrees C was observed in shrimps stored in dry ice at 1:1 ratio. Bacterial flora associated with fresh raw shrimp were Aeromonas, Pseudomonas, Vibrio, Flavobacterium and Serratia. Aeromonas constituted 38% of the flora in raw shrimp. Flavobacterium (43%), Pseudomonas (47%) and Pseudomonas (38%) were the dominant bacterial flora in the shrimp stored in dry ice at 1:1 ratio, in the combination package, and in water ice at 1:1 ratio, respectively.