The Testing and Model Validation of an Additively Manufactured Twisted Tube Heat Exchanger

Performance enhancements in heat exchanger design and manufacturing have been achieved over the past several decades through a combination of improved thermal-hydraulic modeling and experimentation tools, enhancements in material formulations and associated property characterizations, and new manufacturing methods. Most recently, Additive Manufacturing (AM) methods have matured sufficiently that they are now being considered as realizable heat exchanger fabrication methods. More complex, compact, and efficient designs can be achieved with AM methods that could not be easily obtained through more traditional manufacturing techniques. This study expands upon a previous work [1] in which an optimized twisted tube shell and tube stainless steel heat exchanger was designed, analyzed, and fabricated with a Direct Metal Laser Sintering (DLMS) AM method. In that study, the twisted tube heat exchanger performance was a considerable improvement over that of a traditional straight tube shell and tube heat exchanger. In the present study, the AM twisted tube heat exchanger was subjected to thermal-hydraulic tests to measure its performance and to identify any necessary refinements to the previous CFD model. For the conditions used in this study, the experimental data will show how the previous CFD model over-predicted the twisted tube heat exchanger’s heat transfer rate of 2,297 W and under predicted its overall heat transfer coefficient of 1,008 W/m2/K. Interrogation of the CFD model found that this discrepancy was due to the utilization of a k-ε turbulence model. Once this turbulence characterization was replaced with a more suitable shear transport model, the numerical predictions and experimental measurements of total heat transfer rate and overall heat transfer coefficient were in very close (∼10%) agreement. When combined with the previous study, this current work reveals how a complex, twisted tube shell and tube heat exchanger can be designed with existing CFD modeling tools and efficiently manufactured with current AM technologies to significantly improve its performance over a more traditionally manufactured straight tube version of the heat exchanger.

Thermal management for a tube–shell Li-ion battery pack using water evaporation coupled with forced air cooling

A novel battery thermal management system (BTMS) based on water evaporation (WE) and air-cooling (AC) for a tube–shell Li-ion battery (LIB) pack is designed.

Rational construction of a metal core for smart combination with Li4Ti5O12 as integrated arrays with superior high-rate Li-ion storage performance

Co/Li4Ti5O12 arrays with a bamboo joint-like core and hollow tube shell are prepared via ALD-lithiation and they demonstrated excellent high-rate performance.

Magnetic halloysite nanotubes for yeast cell surface engineering

Halloysite clay nanotubes are safe and biocompatible nanomaterials and their application in biomaterials is very promising. The microencapsulation of yeast cells in the shell of clay nanotubes modifying their properties was demonstrated here. Each cell was coated with a 200–300 nm-thick tube shell and this coating was not harmful for these cells’ reproduction. Synthesis of magnetic nanoparticles on the surfaces of the nanotubes allowed for magnetic-field manipulation of the coated cells, including their separation. Providing nano-designed shells for biological cells is a step forward in development of ‘cyborg’ microorganisms combining their intrinsic properties with functions added through nano-engineering.

Simulation of Vapor Absorption of Aqueous Libr Solution on Alternate Heat and Mass Transfer Surfaces of Corrugated Plates and Mesh Pecking

The traditional tube-shell absorber is relatively too bulky to be used in a small absorption chiller for solar air conditioning. As the outer-surface of solution film on the traditional absorber surface is easier to be saturated, several alternate heat and mass transfer absorber schemes have been proposed. However, the film-inversion absorber uses only half surfaces while the dual-side film-inversion absorber scheme is of good performance but too complicated to fulfill. The scheme using stainless steel mesh packing as the film guider is much easier and more uniform in distributing film, and it can also act as the framework for exposing dual-side film to the vapor for adiabatic mass transfer. The alternate heat and mass transfer configurations with plate surfaces and mesh packing are of promising performance for small chiller absorbers.

Research of Shell PTDF Shrink Model

Stress (P) and pressure time (T) are the two main factors which affect the bayonet tube shell shrinking size. In this paper, we study this two factors. Double factors regression analysis and variance analysis method were used to analysis data. PT tube shell shrinkage model is set up to explore the correlation of tube shell shrinkage size and pressure (P) and the pressure time (T) and its change rule. Results show that the established PT contraction model can well reflect the relationship between the tube shell shrinkage size and the PT factors.