On the comparison between computational fluid dynamics (CFD) and lumped capacitance modeling for the simulation of transient heat transfer in solar dryers

Abstract

In this paper transient heat transfer in a solar food drier is modeled by using both computational fluid dynamics (CFD) and lumped capacitance modeling techniques. The CFD model is used to simulate the air flow and transient heat transfer within the dryer. A lumped capacitance model, developed from energy exchanges between various components of the drying chamber, is extensively compared with the results of the CFD model. The two models predict both a 40 ℃ rise in steady-state temperature within the drying chamber. Before reaching this temperature, there is about 8 ℃ RMS deviation between the transient temperature prediction of the two models. This deviation is mainly caused by the heat transfer coefficient around the food rack shelfs. Fitting these coefficients give rise to a minimal RMS deviation between the two models of 1.8℃ and 0.9℃ on the lower and upper rack shelfs respectively. The transient heat transfer phenomenon from CFD modeling also showed that the spatial distribution of temperature after 30 minutes is uniform thus validating the very assumption of lumped capacitance modeling. This demonstrates that the lumped capacitance model can supplant the computationally demanding CFD modeling technique in predicting transient heat transfer phenomenon in solar food dryers.

Simulación de un deshidratador híbrido indirecto activo mediante el software ANSYS

“…Estos modelos pueden ser simples y se pueden resolver analíticamente o, como en este caso, pueden ser modelos de mayor complejidad que utilizan ecuaciones diferenciales. La simulación que se utiliza con la ayuda de CFD genera un modelo matemático con ecuaciones diferenciales que utilizan técnicas numéricas y ordenadores para resolver problemas imposibles de resolver analíticamente (Tegenaw et al, 2019).…”

Computational simulation of soybean particles flow in a hopper using computational fluid dynamics (CFD) and discrete elements method (DEM)

“…Research, Society and Development, v. 9, n. 8, e448985463, 2020 (CC BY 4.0) | ISSN 2525-3409 | DOI: http://dx.doi.org/10.33448/rsd-v9i8.5463 8 CFD simulations have gained prominence in studies of heat, mass, and momentum transfers phenomena in various devices, such as spouted beds (Vieira Neto et al, 2008;Cunha et al, 2009;Bortolotti et al, 2013;Santos et al, 2015;Santos et al, 2017;Batista Junior et al, 2019); fluidized beds (Müller et al, 2009;Araújo & Santos, 2017); fixed beds (Béttega et al, 2013, Rocha et al, 2020Stoppe et al 2020); rotational disk granulators (Vieira Neto et al, 2017); dryer drums (Silvério et al, 2014;Cunha et al, 2016;Gravena et al, 2019); solar dryers (Krawczyk & Badyda, 2011;Tegenaw et al, 2019;Rocha et al, 2020;Stoppe et al 2020); concentric and eccentric annuli (Neto et al, 2011;Vieira Neto et al, 2014); horizontal injector wells (Mantegazini & Romero, 2019) and waste treatment tank (Pereira & Góis, 2020).…”

Analytical Evaluation and Experiment of the Dynamic Characteristics of Double-Thimble-Type Fiber Bragg Grating Temperature Sensors

“…Suppose that the mass and heat capacity of the object originally continuously distributed are concentrated at one point, with only one temperature value. This simplified analysis method that ignores the internal heat conduction and thermal resistance of the object is called the lumped parameter method [ 27 , 28 ].…”