Performance improvement of a horizontal zigzag type mist eliminator using slit plates

Journal of Mechanical Science and Technology - In this study, the performance of a zigzag type mist eliminator with drainage channels was improved using slit plates. The collection efficiency of...     

Lipase-mediated synthesis of neopentyl glycol diester using a combination of reduced and standard pressure

Neopentyl glycol (NPG) diester is a biodegradable lubricant used in the machinery industry as it is suitable for the low-temperature environment. NPG diester was successfully synthesized with fatty acid and NPG using immobilized lipase. Immobilization was carried out with a liquid enzyme, Eversa® Transform 2.0 (from Thermomyces lanuginosus) and Lewatit VP OC 1600 as a carrier. The Eversa immobilized lipase prepared in this study was compared with commercial lipases, such as Novozym 435, Lipozyme RM IM, and Lipozyme TL IM. The Eversa immobilized lipase was the most effective biocatalyst for the synthesis of NPG diesters. The effects of enzyme loading and temperature on conversion were explored at a standard pressure of 101.3 kPa. And then, the effect of reduced pressure was investigated in the range of 1.3 to 40.0 kPa under optimum conditions obtained at standard pressure. The maximum conversion of ca. 63% was achieved at the optimal temperature of 50°C and the enzyme loading of 5% (based on the total weight of the substrate) at standard pressure after 10 h. However, the conversion to NPG diester increased markedly up to 97% after 10 h, even though reduced pressure as low as 26.7 kPa was applied. No significant differences in the conversion to NPG diester between the reactions at constant reduced pressure and the combined reaction of reduced pressure and standard pressure were observed. This pressure combination method employed in this study demonstrated a novel, energy-saving strategy for the synthesis of NPG diester.     

Search heuristics for a parallel machine scheduling problem with ready times and due dates

We consider a problem of scheduling orders on identical parallel machines. An order can be released after a given ready time and must be completed before its due date. An order is split into multiple jobs (batches) and a job is processed on one of the parallel machines. The objective of the scheduling problem is to minimize the holding costs of orders including work-in-process as well as finished job inventories. We suggest two local search heuristics, simulated annealing and taboo search algorithms, for the problem. Performance of the suggested algorithms is tested through computational experiments on randomly generated test problems.