Invention Journal of Research Technology in Engineering & Management (IJRTEM) www.ijrtem.com ǁ Volume 1 ǁ Issue 9 ǁ
ISSN: 2455-3689
Optimization of shell thickness of sub-baric Fryer for manufacture of fried food products using Finite Element Analysis (FEA) Mahesh kumar G1. Menon Rekha Ravindra2 1
Asst. Professor of Dairy Engineering, Dairy Science College, Hebbal, Bengaluru- 560024 2 Senior Scientist, SRS-NDRI Bengaluru -560030
Abstract: Sub-baric thermal fryer (SBTF) is vacuum frying equipment used for frying of food products like snack and sweets. It is cylindrical in geometry designed to work at different temperatures and vacuum levels. 160 ºC at 5 kPa pressure (vacuum). The cylindrical frying vessel is exposed to atmospheric pressure on the outside which leads to compressive forces acting on inside wall the fryer. The stresses developed will have direct bearing on shell thickness of the cylinder wall. There will be implosion of SBTF when Von Mises stress generated is greater than yield stress of the metal which is stainless steel (205MPa). Wall thickness of SBTF was optimized by Finite Element Analysis (FEA) by model development and simulation in Pro/ENGINNER. ANSYS-14 was used for Von Mises stress analysis, deformation and factor of safety. The wall thickness of shell was analyzed by hyper tetrahedron meshing. To validate the shell thickness, design software which uses ASME approved design equation was used for calculation. The model prediction was shown to be in good agreement with analytical calculation. The FEA resulted in Von Mises stress of 135.79 Mpa, a deformation of 1.55 mm and factor of safety of 1.5. With the results of the analysis, SBTF was fabricated as per FDA C-GMP standards from 4 mm thick AISI-316 SS. The fabricated equipment was subjected to various design and safety standard tests and found to work satisfactorily reconfirming validation of the design. Keywords: Sub-baric thermal fryer, vacuum frying, ANSYS, PRO/ENGINEER, Gulabjamun frying
INTRODUCTION: Sub-baric thermal frying (SBTF) or vacuum frying is a novel and innovative technology used in many countries for manufacture of healthy and nutritious deep fried food products. The vacuum fried food products will have less oil uptake and without acrylamide (a compound which is reported to be carcinogenic and neurotoxin). The process has an added advantage of reuse of frying oil for many repeated cycles, with least Hydroxyl methyl furfural (HMF) production and without trans-fat formation. This process and technology is recent, novel and first of its kind that was tried in the dairy industry. Gulabjamun was the specific dairy product considered for processing in this study though the equipment developed could also be used for preparation of other similar deep fried food products. SBTF is vacuum frying equipment used for frying of Gulabjamun under full vacuum. From functional requirements, SBTF was to be fabricated from AISI-316 as per FDA C-GMP standards. The fryer is in cylindrical in geometry designed to work at 160ºC at 5 kPa pressure (vacuum).
Fig. 1.1 Direction of Internal pressure SBTF is exposed to atmospheric pressure on outside which leads to compressive forces acting on inside leading to buckling (Fig. 1.1). The mechanical strength of the SBTF was determined by the thickness of the metal sheet (wall thickness) used in its fabrication which is the critical design parameter. There will be implosion when stress developed is more than yield stress of SS316, the material used in the design. The following design steps elaborate the procedures adopted for FEA and optimization of shell thickness of Sub-baric thermal fryer.
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