Fired equipment suffers from local overloading and fouling of heat transfer surfaces, products are not of the required quality, and operating costs are increased due to the high pressure drop of process fluids. Such operational issues are affected by the non-uniform distribution of fluid flow and heat flux variability. Detailed numerical analyses are often applied to troubleshoot these problems. However, is this common practice effective? Is it not better to prevent problems from occurring by using quality equipment design? It is, according to the general consensus. Still, the experience of designing fired apparatuses reveals that the established standards do not reflect the real maldistribution sufficiently. In addition, as found from the given overview of modelling approaches, the radiant chamber and the convection section are usually analysed separately without significant continuity. A comprehensive framework is hence introduced. The proposed procedure clearly defines the interconnection of traditional thermal-hydraulic calculations and low-cost modelling systems for radiant and convection sections. A suitable combination of simplified methods allows for the reliable design of complex equipment and fast identification of problematic areas. The utilisation of selected low-cost models, i.e., the second phase of the systematic framework, is presented regarding the example of a steam boiler.

A new strategy for fast, approximate analyses of fluid flow and heat transfer is presented. It is based on Finite Element Analysis (FEA) and is intended for large yet structurally fairly simple heat transfer equipment commonly used in process and power industries (e.g., cross-flow tube bundle heat exchangers), which can be described using sets of interconnected 1-D meshes. The underlying steady-state model couples an FEA-based (linear) predictor step with a nonlinear corrector step, which results in the ability to handle both laminar and turbulent flows. There are no limitations in terms of the allowed temperature range other than those potentially stemming from the usage of fluid physical property computer libraries. Since the fluid flow submodel has already been discussed in the referenced conference paper, the present article focuses on the prediction of the tube side and the shell side temperature fields. A simple cross-flow tube bundle heat exchanger from the literature and a heat recovery hot water boiler in an existing combined heat and power plant, for which stream data are available from its operator, are evaluated to assess the performance of the model. To gain further insight, the results obtained using the model for the heat recovery hot water boiler are also compared to the values yielded by an industry-standard heat transfer equipment design software package. Although the presented strategy is still a “work in progress” and requires thorough validation, the results obtained thus far suggest it may be a promising research direction.

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Requirements of modern process and power technologies for compact and highly efficient equipment for transferring large heat fluxes lead to designing these apparatuses as dense parallel flow systems, ranging from conventional to minichannel dimensions according to the specific industrial application. To avoid operating issues in such complex equipment, it is vital to identify not only the local distribution of heat flux in individual parts of the heat transfer surface but also the uniformity of fluid flow distribution inside individual parallel channels of the flow system. A composite modelling system is currently being developed for accurate design of such complex heat transfer equipment. The modeling approach requires a flow distribution model enabling to yield accurate-enough predictions in reasonable time frames. The paper presents the results of complex experimental and modeling investigation of fluid flow distribution in dividing headers of tubular-type equipment. Different modeling approaches were examined on a set of header geometries. Predictions obtained via analytical and numerical models were validated using data from the experiments conducted on additively manufactured header samples. Two case studies employing parallel flow systems (mini-scale systems and a conventional-size heat exchanger) demonstrated the applicability of the distribution model and the accuracy of the composite modelling system.