This presentation was made at the NAFEMS European Conference on Simulation-Based Optimisation held on the 15th of October in London.
Optimisation has become a key ingredient in many engineering disciplines and has experienced rapid growth in recent years due to innovations in optimisation algorithms and techniques, coupled with developments in computer hardware and software capabilities. The growing popularity of optimisation in engineering applications is driven by ever-increasing competition pressure, where optimised products and processes can offer improved performance and cost-effectiveness which would not be possible using traditional design approaches. However, there are still many hurdles to be overcome before optimisation is used routinely for engineering applications.
The NAFEMS European Conference on Simulation-Based Optimisation brings together practitioners and academics from all relevant disciplines to share their knowledge and experience, and discuss problems and challenges, in order to facilitate further improvements in optimisation techniques.
Hillphoenix, a division of Dover Company, manufactures display cases designed to showcase and store the products at desired thermal condition with less energy consumption. The design and manufacturing of energy efficient display case is a continuous goal for Hillphoenix. Innovative design changes and implementation of cutting-edge technologies are required to achieve this goal. The simulations become a virtual platform to achieve an optimized design at lesser time and cost. In this paper, design and optimization of an air-curtain generator for the remote display case with a glass door, using computational fluid dynamics simulation (CFD) is discussed.
For simulations, the computational domain of the display case consisted of an evaporator, fan, honeycomb, products, perforated back flue panel, glass door, shelves, support structures, and outer frames. The fan and the honeycomb were simplified and modelled as fan boundary and porous domain, respectively. Thin support structures, shelves, back flue panel, top flue panel and evaporator fins are modeled as zero thickness wall. The three pane, argon filled glass door is also simplified as single pane glass door with equivalent thermal properties. A conformal hybrid mesh of around 29 million elements is generated with acceptable quality. A steady state, conjugate heat transfer analysis is performed for this model for validation. A realizable k-ε turbulence model with scalable wall function, DO radiation model and variable density model with gravity are the models used to calculate the effect of turbulence, radiation and buoyancy, respectively. The temperatures at the honeycomb discharge, return grille and products at critical locations are predicted from this baseline CFD simulation and are found to be within 4% with the measured test data.
Based on first principles, several new design concepts are identified to meet the objective. For the selected concept, a multi-objective design optimization is performed. The discharge air velocity (uniform and maximum), discharge air turbulence (minimum) and discharge air jet length (maximum; without detaching from product side) are the performance parameters and criterion used for improving the air curtain performance. The design parameters for optimization are exit length, outlet width, and turning guide gap ratio. The minimum to maximum ranges of these parameters are also defined. The effect of design parameters on performance parameters are analyzed using pareto chart, normal plot and main effect plot. The response surface optimization technique is used to obtain the optimum solution. The optimized design thus obtained provided about 20% increase in air-curtain performance. The increased air-curtain performance will potentially reduce the energy consumption of the display case. This work demonstrates an effective use of simulations to achieve an optimized design for the business.
|Date||15th October 2019|