• Plate heat exchanger design: a case study for ventilation systems of small residences

    Innovations, Vol. 7 (2019), Issue 2, pg(s) 60-65

    In this study, a plate heat exchanger (PHE) was designed to meet the ventilation requirements in a small dwelling by performing heat recovery. In the Taguchi analysis performed by selecting three-level four effective parameters, L9 orthogonal array was used. In the analysis, the optimal levels of the design variables were determined by using Computational Fluid Dynamics (CFD) results in order to maximize the combined thermal and hydrodynamic effectiveness (CTHE) selected as the performance parameter. The CTHE was defined as the multiply of thermal effectiveness and flow effectiveness of the PHE. The 3-dimesional CFD models of the PHE were designed to include the effects of the local change in the flow cross-section, which will occur at the inlet-outlet of the air flow channels. Thermal and hydrodynamic computation of PHE models were obtained by finite volume software. In Taguchi analysis, design variables and levels that maximize CTHE: sub-channel number-6, channel height-3 mm, average air flow rate-2 m/s and plate material is paper. When the CTHE predicted from Taguchi analysis was compared with that solution of the CFD model generated using the optimized design and operating parameters, the difference was determined to be less than 1%. In addition, in order to calculate the CTHE based on the design variables, a mathematical equation was obtained in a 90% confidence interval.



    Machines. Technologies. Materials., Vol. 12 (2018), Issue 4, pg(s) 143-148

    This study, considering need of fresh air in the air-conditioning system in a small residence, geometrical dimensions of a flow nozzle and an orifice plate were determined by theoretical equations in the literature. The measurement performances of designed flow meters were compared with numerical method using Computational Fluid Dynamics (CFD). The measured air flow rate is in the range of 80-300 m3/h and Reynolds numbers at the inlet of flow meters are 12,000-46,000. The β ratio of designed flow meters is chosen to be  0.45  in order to avoid excessive increase of pressure drop. Three dimensional numerical models were created to control the accuracy of flow
    meters. The results from numerical solution show that permanent pressure loss in the orifice plate is 2.6 times greater than the flow nozzle. Lower pressure and energy loss occur in the flow nozzle compared to the orifice plate. In a system where continuous measurement for the purpose of velocity control of fans is carried out, it has been found that electric power consumption of the fans will increase by 4.85 W and 12.42 W, respectively, at the flow rates of 150 and 200 m3/h for flow nozzle.