Improving the Designing Method of Thermal Networks: Serial Connection of Streams

Abstract

The paper presents an approach to the design of technical systems, the elements of which are interconnected and carry out an internal exchange of energy. The above analysis showed that for heat-exchange equipment when combining devices into systems, only iterative methods are currently used, a representative of which is Pinch analysis. A limitation of the iterative approach is the impossibility of obtaining an exact solution to such problems, which can only be achieved by analytical methods, which also make it possible to reveal some effects in systems that are practically unavailable for numerical solution. This indicates the absence of a rigorous proof of the existence of a solution and a problem in the construction of approximate solutions, due to the need to involve complementary hypotheses. The topological representation of the system modules allows us to consider the architecture as a network, which contributes to the analysis of the connections between the constituent elements and the identification of their mutual influence. Highlighted the typical connections of network elements such as serial, parallel, contour, which allows to unify the principles of building connections in the system. As an optimality criterion, the NTU parameter was chosen, which includes the heat exchange surface and is usually used when searching for a solution for heat exchangers of moving objects. An analytical solution to the problem of flow distribution and energy exchange efficiency in a system of two series-connected heat exchangers is obtained. His analysis showed that the formulation of the design problem based on the definition of matrix elements in relation to determinants allows not only to meet the requirements for the system, but also to determine the design parameters of its elements that satisfy their extreme characteristics

Modeling of thermal processes in vertical heat exchangers of ground-source heat pump

“…The value of COP=4.3 is significantly higher than the typical values given in [17,18], [19], which indicates the high efficiency of the cycle in Fig. 3.…”

“…Results of numeric simulation obtained using refined calculation [17] based at new data that are shown in Fig. 6.…”

Improving the designing method of thermal networks: bypass connection

“…The key factor that determines both the operation of the designed system and its elements is the correspondence of the direction of the processes in the real system with their direction hypothetically chosen by the designer when specifying its topology. It is well known that the direction of processes and their performance is determined by the second law of thermodynamics and, as a consequence, is associated with the uncertainty of the values of average energy measures both in the elements of the system and in its networks [16,17]. In other words, the distribution of the energy potential dictates the conditions for the operability of the system and its elements through the uncertainty of the values of the average energy measures.…”