Optimal design of mass timber panels as dynamic insulation: simulations of steady and transient heat exchange

Mass timber panels could be designed as heat exchangers for use in building envelopes. Fresh air, drawn through geometrically optimized channels in the panel, is pre-tempered with building heat that would otherwise be lost to the exterior via conduction. Recent experiments have shown that timber heat exchanging panels can approach U ~0.1 W/m2K – but there are potential limitations. The sizing correlations which predict panel geometry and steady heat exchange must be numerically calibrated for building-scale contexts, the heat-exchange efficiency must be verified virtually, and practical thresholds for transient response time must be determined. This study uses numerical simulations to investigate these factors for one design ‘case’ of timber panels, and establishes a methodology for studies of further cases.

Research on Localization of Serpentine Tube High Pressure Heater

It could be seen that the ultra supercritical reheating is a high-end technology in the field of power equipment manufacturing, which represents the strength and design level of national major equipment manufacturing industry. Based on the development of key components technology of millions of secondary reheat units, solving the design and manufacturing problems of serpentine high-pressure heater, optimizing the heat exchange efficiency of serpentine high-pressure heater, and improving the operation reliability, will help to promote the development process of China’s high-end power equipment, and provide important technical support for the quality supervision and management of serpentine high-pressure heater.

Air curtain based on coupling of air source heat pump and electric heating

Air curtain is a widely used heat insulation equipment in the market, which reduces the heat exchange efficiency of both sides by the air surface formed by jet. In order to reduce the use of electric heating device in air curtain, a new air curtain is designed by the coupling experiment of air source heat pump and electric heating. The air curtain fan is preheated by the condenser of air source heat pump, so as to reduce the dependence of air curtain on electric heating parts, and save energy consumption.

A Three-Dimensional Numerical and Multi-Objective Optimal Design of Wavy Plate-Fins Heat Exchangers

This paper presents a method for optimizing wavy plate-fin heat exchangers accurately and efficiently. It combines CFD simulation, Radical Basis Functions (RBF) with multi-objective optimization to improve the performance. The optimization of the Colburn factor j and the friction coefficient f is regarded as a multi-objective optimization problem, due to the existence of two contradictory goals. The approximation model was obtained by Radical Basis Functions, and the shape of the heat exchanger was optimized by multi-objective genetic algorithm (MOGA). The optimization results showed that j increased by 17.62% and f decreased by 20.76%, indicating that the heat exchange efficiency was significantly enhanced and the fluid structure resistance reduced. Then, from the aspects of field synergy and tubulence energy, the performance advantage of the optimized structure was further confirmed.

Numerical Simulation and Field Synergy Analysis of IGBT Air-Cooled Heat Exchanger for EMUs

In view of the heat transfer and ventilation characteristics of the Insulated Gate Bipolar Transistor (IGBT) in the Electric Multiple Unit (EMU), the authors aim to improve the traditional fin structure of the air-cooled heat exchanger (ACHE) and propose the use of corrugated fin structure. Using the computational fluid dynamics (CFD) technology, the ACHE with new fin structure was numerically simulated, and the temperature field, velocity field and pressure field at different fin corrugation angles and the synergy between the fields were analyzed. The results show that the improved fin structure can make the fluid flow in a corrugated flow channel, effectively increase the flow distance, and thus significantly enhance the turbulence performance of the fluid in the ACHE; the fin corrugation angle of 120 degrees is the key design point; compared with the traditional fin structure, the new fin structure improves the synergy between the various fields and increases the heat exchange efficiency. The research findings provide new ideas for the design of this type of ACHE.

Designing an evaporator station with effects consisting of two or more vessels

Analysis and comparison were carried out for evaporator stations having a 4th effect consisting either of two falling-film type vessels or two vessels of different designs – one Robert and one falling-film. The influence of the order, in which two apparatuses are installed in a serial layout in the 4th effect on the evaporation efficiency was analysed. A 4th effect consisting of 2 vessels was also compared to a 4th effect consisting of one vessel. The characteristics of 4th effect with one apparatus are used as a reference point for this analysis. Significant differences were found in the heat exchange efficiency of the analysed variants. It is worth carrying out an analysis when designing the modernization/extension of an evaporator station in order to obtain an optimal layout under specific conditions.

A Study of Heat Exchange Processes within the Channels of Disk Pulse Devices

The effect of basic parameters of the channels of disk pulse devices on the heat exchange efficiency was studied both analytically and experimentally, especially in terms of pulse acting on the heat carrier. A methodology to determine the main parameters, namely the pressure and the temperature of the heat carrier as well as the pulse effect on the fluid, was proposed. The mathematical models of the effect of the structural and technological parameters of the channels in the disk pulse device on the heat exchange efficiency were developed. The models’ adequacy was proved based on a series of experimental studies involving devices with one-stage and multistage systems of pulsed heat carrier processing. This enabled the development, testing, and implementation of practical construction designs of pulse disk heat generators for decentralized heating of commercial and domestic buildings with one-stage and multistage systems of pulsed heat carrier processing. Taking into account the results of the mathematical modeling, the developed method of multistage pulse action was proved experimentally and implemented in regard to the structural design of a working chamber of the disk pulse heat generator. An efficient geometry of the working chamber of the disk pulse heat generator was specified for its further integration into the system of decentralized heat supply. One of the developed heat generators with the multistage pulse action on the heat carrier was integrated into the heating system of a greenhouse complex with a 0.86–0.9 efficiency coefficient.

Multiple-relaxation-time lattice Boltzmann simulation of natural convection with multiple heat sources in a rectangular cavity

Natural convection and heat transfer in a square cavity with multiple heat sources was investigated through a multiple-relaxation-time (MRT) collision model and lattice Boltzmann method (LBM) in the current work. The MRT-LBM model was verified by a former experiment and numerical findings with different Ra numbers from 103 to 105, which proved the MRT-LBM model is effective to handle the flow and transfer. The heat transfer that developed inside the cavity was analyzed under different width, height, and lateral offset of heat source in this paper. Moreover, the change of spacing between two symmetrically distributed heat sources was discussed. The results showed that the heat exchange efficiency was augmented by increasing width, height, and spacing of the heater, but it was reduced by increasing lateral offset. Specifically, the Nusselt number of the upper wall decreased by increasing height of heat source, and the left and right walls showed better heat exchange efficiency by increasing height. Additionally, the lateral position had a notable influence on the left wall surface of the heat source, and the optimum heat exchange efficiency of the heat source’s left wall existed in the condition of small lateral offset.