Two figures of merit for hybrid Thermal Energy Storage (TES) units are developed: the volumetric figure of merit, V~ , and the temperature control figure of merit, T~ ∆ . A dimensional analysis shows that these quantities are related to the performance specification of the storage unit and its physical design. A previously benchmarked semi-empirical finite volume model is used to study the char...

A numerical model has been developed to simulate coupled thermal and electrical energy transfer processes in a thermoelectric generator (TEG) designed for automotive waste heat recovery systems. This model is capable of computing the overall heat transferred, the electrical power output, and the associated pressure drop for given inlet conditions of the exhaust gas and the available TEG volume....

the performance of a γ-al 2 o 3 /n-decane nanofluid shell-and-tube heat exchanger in a biomass heating plant is analyzed to specify the optimum condition based on the maximum heat transfer rate and performance index for wide range of nanoparticle volume fraction (0–7%). compared with pure          n-decane, the obtained results in this research show that by using γ-al 2 o 3 /n-decane nanofluid ...

longitudinal heat conduction is an important parameter in the cryogenic field, especially in cryogenic heat exchangers. in the present work, the parasitic effect of tube wall longitudinal heat conduction on temperature measurement has been studied in cryogenic laminar hydrogen flow. the effects of various parameters such as wall cold end temperature, wall thermal conductivity, gas volumetric fl...

If an air flow is injected into a liquid fluid, many ambulant air bubbles are formed inside the fluid. Air bubbles move inside the liquid fluid because of the buoyancy force, and the mobility of these air bubbles makes sizable commixture and turbulence inside the fluid. This mechanism was employed to enhance the heat transfer rate of a horizontal double pipe heat exchanger in this paper. Howeve...

This paper deals with the derivation of a low-dimensional mathematical model of a compact plate heat exchanger capturing the significant nonlinearities and the essential dynamic behavior in an accurate way. Thereby, the model is based on the basic laws of thermodynamics and the similitude theory of Nußelt. It is shown that reasonable simplifications according to the specific design and the typi...

The deterioration of the performance of a cross flow heat exchanger with condensation due to the longitudinal conduction was investigated. For a relatively small change of wall temperature along the flow directions which was shown to be common in many applications, the energy equations were solved numerically. An iterative method was used to solve the resulting equations of the finite differenc...

Joule-Thomson cooling systems are used in refrigeration and liquefaction processes. There are extensive studies on Joule-Thomson cryogenic systems, but most of them coverage steady state conditions or lack from experimental data. In the present work, transient thermal behavior of Joule-Thomson cooling system including counter current helically coiled tube in tube heat exchanger, expansion valve...