Temperature Profiles within a Double‐pipe Heat Exchanger with Countercurrent Turbulent Flow of Newtonian Fluids: Derivation, Validation, and Application to Food Processing

Abstract

Pasteurization or sterilization of food and bioproducts is mostly performed using heat exchangers in countercurrent flow. The lack of appropriate analytic solutions for temperature profiles in the heating and cooling sections of such processes is most likely the main reason for the traditional cautious approach of disregarding the contribution of these stages in the total thermal history calculation. This approach leads to excessive thermal abuse of the product. The current manuscript describes the derivation and validation of an analytic solution for the temperature profiles within a double-pipe heat exchanger with countercurrent turbulent flow of Newtonian fluids, at any possible flow rate and not necessarily assuming an isothermal heating medium or coolant. The presented solution is based on application of the "heat exchanger effectiveness" concept in a partial heat exchanger, and can be easily solved and plotted using a spreadsheet. An interactive Excel TM workbook was developed for fast prediction of temperature profiles and used in a simulated case study to demonstrate the influence of operating conditions on the temperature profile and thermal history of a pasteurized liquid product.

Modeling of continuous thermal processing of a non-Newtonian liquid food under diffusive laminar flow in a tubular system

“…Heat transfer, residence time distribution, fluid flow and rheology are important factors that have been studied so that it could be possible to improve the knowledge of the mechanisms associated with the 0017-9310/$ -see front matter Ó 2012 Elsevier Ltd. All rights reserved. http://dx.doi.org/10.1016/j.ijheatmasstransfer.2012.05.075 thermal processing of food products [14,[21][22][23][24][25][26][27][28]. Moreover, modeling and simulation tools have been applied for the study, evaluation and optimization of continuous thermal processing of foods [8,11,13,[29][30][31].…”

“…The usual simplification is to consider an isothermal holding tube with plug-flow at the maximum velocity (minimum residence time at the center of the tube). This conservative approach leads to a safe, but over-processed food that can have low acceptance by the consumer [11,[13][14][15][16][17]. The residence time distribution associated with the laminar flow velocity profile can be included in the lethality calculation for a better design of the holding tube under isothermal conditions [18].…”

Nanofluid as the working fluid of an ultrasonic-assisted double-pipe counter-flow heat exchanger

“…DPHXs are used in different applications like food [3,4], gas, oil, and chemical industries [5]. In general, heat transfer enhancement methods are classified into three main methods: (1) passive, (2) active, and (3) compound methods.…”

“…) double pipe heat exchanger, (2) pump,(3) heater, (4) piezoelectric transducers and Ultrasonic generators,(4) hot fluid flow circuit, and (6) Cold fluid flow circuit. The heat exchanger section consists of two concentric pipes of counter flow type and made of steel, in which hot fluid passes through the inner tube, and cold fluid flows in the outer tube.…”

Thermal and fluid flow first-principles numerical design of an enhanced double pipe heat exchanger

“…There is in parallel a number of publications that are concerned with applications. Typical of this group are [22][23][24], which relate to food and chemical processing in general.…”