Thermal Performance of Heat Pipe Drill: A New Simulation Model for Heat Pipe

2005 ◽  
Author(s):  
Tien-Chien Jen ◽  
Quan Liao ◽  
Qinghua Chen ◽  
Longjian Li ◽  
Wenzhi Cui
Keyword(s):  
Heat Pipe ◽  
High Reliability ◽  
Heat Removal ◽  
Simulation Models ◽  
Work Piece ◽  
Drilling Process ◽  
Confined Space ◽  
Machining Processes ◽  
Dry Drilling ◽  
Pipe Model

It is well known that drilling is one of the most difficult metalwork cutting operations, not only from the viewpoint of manufacturing process, but also from the thermal management point of view of the drill. For the drilling process, due to its long time continuous metal-to-metal friction between drill tip edge and work piece, a significant amount of heat is generated on the interface, which is in a confined space compared to other machining processes, such as cutting or milling. This makes it very difficult to keep the temperature of drill tip under a certain but acceptable range since the coolant is unable to penetrate deep enough into the hole. Also, based on the environmental considerations and the cost reduction requirement, the conventional flooding coolant method become highly inefficient and expensive due to high maintenance costs. A new approach, dry drilling method (i.e., no coolant is employed during the drilling process) is investigated in this study. In dry drilling, we used heat pipe technology to accomplish the goal of efficient heat removal from the drill tip. It is heat pipe’s unique and excellent advantages such as, high reliability, supreme equivalent thermal conductivity, flexible adaptability and so forth, that make it possible for dry drilling by combining the drill and heat pipe. From the numerical simulation viewpoint of heat pipe drill, how to correctly model the heat pipe in the drill is one of the crucial tasks because it will directly influence the accuracy of the simulation results. So far, there are few different kinds of simulation models for heat pipe drill and each of them works well in some kinds of special situations. The present paper studied and compared these different simulation models of heat pipe and then proposed a general, simple but robust and more accurate approach to simulate the heat transfer process in the heat pipe drill. Furthermore, this kind of the heat pipe model can be used in many other heat pipe applications.

scholarly journals Performance Analysis of Hybrid Desiccant Cooling System with Enhanced Dehumidification Capability Using TRNSYS

2021 ◽  
Vol 11 (7) ◽  
pp. 3236
Author(s):  
Ji Hyeok Kim ◽  
Joon Ahn
Keyword(s):  
Thermal Comfort ◽  
Cooling System ◽  
Operation Mode ◽  
Heat Removal ◽  
Simulation Models ◽  
Coefficient Of Performance ◽  
Dimensional Structure ◽  
Dominant Factor ◽  
Exhaust Heat ◽  
Chp System

In a field test of a hybrid desiccant cooling system (HDCS) linked to a gas engine cogeneration system (the latter system is hereafter referred to as the combined heat and power (CHP) system), in the cooling operation mode, the exhaust heat remained and the latent heat removal was insufficient. In this study, the performance of an HDCS was simulated at a humidity ratio of 10 g/kg in conditioned spaces and for an increasing dehumidification capacity of the desiccant rotor. Simulation models of the HDCS linked to the CHP system were based on a transient system simulation tool (TRNSYS). Furthermore, TRNBuild (the TRNSYS Building Model) was used to simulate the three-dimensional structure of cooling spaces and solar lighting conditions. According to the simulation results, when the desiccant capacity increased, the thermal comfort conditions in all three conditioned spaces were sufficiently good. The higher the ambient temperature, the higher the evaporative cooling performance was. The variation in the regeneration heat with the outdoor conditions was the most dominant factor that determined the coefficient of performance (COP). Therefore, the COP was higher under high temperature and dry conditions, resulting in less regeneration heat being required. According to the prediction results, when the dehumidification capacity is sufficiently increased for using more exhaust heat, the overall efficiency of the CHP can be increased while ensuring suitable thermal comfort conditions in the cooling space.

scholarly journals Temperature monitoring in the subsurface during single lip deep hole drilling

2020 ◽  
Vol 87 (12) ◽  
pp. 757-767
Author(s):  
Robert Wegert ◽  
Vinzenz Guski ◽  
Hans-Christian Möhring ◽  
Siegfried Schmauder
Keyword(s):  
Cutting Parameters ◽  
Drill Hole ◽  
Machining Process ◽  
Hole Drilling ◽  
Drilling Process ◽  
Deep Hole ◽  
Machining Processes ◽  
Deep Hole Drilling ◽  
Feed Force ◽  
Cutting Zone

AbstractThe surface quality and the subsurface properties such as hardness, residual stresses and grain size of a drill hole are dependent on the cutting parameters of the single lip deep hole drilling process and therefore on the thermomechanical as-is state in the cutting zone and in the contact zone between the guide pads and the drill hole surface. In this contribution, the main objectives are the in-process measurement of the thermal as-is state in the subsurface of a drilling hole by means of thermocouples as well as the feed force and drilling torque evaluation. FE simulation results to verify the investigations and to predict the thermomechanical conditions in the cutting zone are presented as well. The work is part of an interdisciplinary research project in the framework of the priority program “Surface Conditioning in Machining Processes” (SPP 2086) of the German Research Foundation (DFG).This contribution provides an overview of the effects of cutting parameters, cooling lubrication and including wear on the thermal conditions in the subsurface and mechanical loads during this machining process. At first, a test set up for the in-process temperature measurement will be presented with the execution as well as the analysis of the resulting temperature, feed force and drilling torque during drilling a 42CrMo4 steel. Furthermore, the results of process simulations and the validation of this applied FE approach with measured quantities are presented.

scholarly journals Dispositivos De Interrupcion Subia (Dis) Para El Analisis De Raices Viruta

2014 ◽  
Vol 2 (2) ◽  
Author(s):  
Diego Alejandro Neira Moreno
Keyword(s):  
Cutting Tool ◽  
Cutting Tools ◽  
Scientific Research ◽  
Cutting Process ◽  
Work Piece ◽  
Mechanical Forces ◽  
Machining Processes ◽  
Research Instrument ◽  
Machined Parts ◽  
Interaction Phenomena

El estudio de las variables y efectos derivados del mecanizado provee herramientas de conocimiento tendientes a optimizar el uso de las herramientas y los procedimientos de maquinado industrial. Este artículo de reflexión aborda el uso de los dispositivos de interrupción súbita (DIS) como herramientas de obtención de raíces de viruta para la investigación científica del mecanizado industrial, y para el estudio de los efectos derivados de la interacción entre las herramientas de corte y el material de trabajo, en función de los cambios microestructurales del material de trabajo, dependientes de la temperatura producida y los esfuerzos mecánicos de la herramienta de corte durante el mecanizado. Mediante la reflexión se destaca la importancia de los DIS como instrumentos de investigación científica en la manufactura, ya que estos permiten obtener muestras de viruta para estudiar las variables incidentes en el maquinado y a partir de esta evidencia, proponer alternativas para optimizar la fabricación de piezas y la integridad de las herramientas empleadas en el proceso.AbstractThe study of the variables and effects derived from the machining processes brings the knowledge needed to optimize the use of machining tools and procedures. This article is an opinion piece about the use of quick stop devices (QSD) as a scientific research instrument in machining projects to obtain chip roots, to study the interaction phenomena between cutting tool and work piece material that depends on temperature and the mechanical forces produced by the cutting tool during the cutting process. This article deals about how important the QSD are as a research instruments in manufacture because with this instruments it is possible to analyze the machining variables, based on the evidences bring by the chip roots obtained with the instrument. It is possible to propose optimization alternatives in the manufacture of machined parts and the integrity of cutting tools.

System Identification of the High Performance Drilling Process for Network-Based Control

2007 ◽  
Author(s):  
Rau´l M. del Toro ◽  
Michael C. Schmittdiel ◽  
Rodolfo E. Haber-Guerra ◽  
Rodolfo Haber-Haber
Keyword(s):  
Dynamic Behavior ◽  
Feed Rate ◽  
Network Architecture ◽  
High Performance ◽  
Control Strategies ◽  
Input Function ◽  
Resultant Force ◽  
Work Piece ◽  
Drilling Process ◽  
Force System

A simple, fast, network-based experimental procedure for identifying the dynamics of the high-performance drilling (HPD) process is proposed and successfully applied. This identification technique utilizes a single-input (feed rate), single-output (resultant force) system with a dual step input function. The model contains the delays of both the network architecture (a PROFIBUS type network) and the dead time related with the plant dynamic itself. Classical identification techniques are used to obtain first order, second order, and third order models on the basis of the recorded input/output data. The developed models relate the dynamic behavior of resultant force versus commanded feed rate in HPD. Model validation is performed through error-based performance indices and correlation analyses. Experimental verification is performed using two different work piece materials. The models match perfectly with real-time force behavior in drilling operations and are easily integrated with many control strategies. Furthermore, these results demonstrate that the HPD process is somewhat non-linear with a remarkable difference in gain due to work piece material; however, the dynamic behavior does not change significantly.

WC-Co Tool Failure Analysis and the Grinding Effect Study

2010 ◽  
Vol 139-141 ◽  
pp. 269-273 ◽  
Author(s):  
Xiu Xu Zhao
Keyword(s):  
Residual Stress ◽  
Effect Study ◽  
Work Piece ◽  
Grinding Process ◽  
X Ray Diffraction ◽  
Machining Processes ◽  
Tool Failure ◽  
Micro Cracks ◽  
Comparison Results ◽  
Grinding Conditions

Grinding is one of the important machining processes for the WC-Co carbide product. Different grinding strategies will have different impact on the work piece material. This study focuses on the WC-Co carbide grinding process, and the effect of grinding condition on the WC-Co carbide microstructure, figures out the relationship between different grinding strategies and material microstructure which relate to the WC-Co carbide tool failure. A specific microstructure analysis with Scanning Electric Microscope (SEM) will be presented based on a series of grinding experiments. The residual stress that generated in the grinding process will also be discussed based on the X-Ray Diffraction (XRD) measurements. It has been found that micro cracks are generated at certain grinding conditions with certain level. The residual stress which generated in the grinding process can be calculated by the d-spacing shift, and the comparison results show micro-cracks level is corresponding with the peaks shift in XRD test.

Real Time Experimental Performance Assessment of a Photovoltaic Thermal System Cascaded with Flat Plate and Heat Pipe Evacuated Tube Collector

2021 ◽  
pp. 1-28
Author(s):  
Laveet Kumar ◽  
Md Hasanuzzaman ◽  
Nasrudin Abd Rahim
Keyword(s):  
Performance Assessment ◽  
Flat Plate ◽  
Heat Pipe ◽  
Large Scale ◽  
Industrial Process ◽  
Simulation Models ◽  
Solar Thermal ◽  
Evacuated Tube Collector ◽  
Flat Plate Collector ◽  
Evacuated Tube

Abstract In response to the global quest for a sustainable and environmentally friendly source of energy most scientists' discretion is solar energy, especially solar thermal. However, successful deployment of solar thermal technologies such as solar assisted process heating (SAPH) systems in medium- to large-scale industries is still in quandary due to their inefficacy in raising ample temperatures. Cascaded SAPH system, which is essentially a series combination of two same or different types of thermal collectors, may provide a worthwhile solution to this problem. In this article, performance assessment and comparison of two cascaded SAPH systems have been presented: photovoltaic thermal (PVT) cascaded with flat-plate collector (PVT-FPC) and PVT coupled with heat-pipe evacuated tube collector (PVT-HPETC). Simulation models have been presented for individual FPC, HPETC and PVT as well as PVT cascaded with FPC and HPETC systems in TRNSYS and validated through outdoor experimentation. Both the first and the second laws of thermodynamics have been employed to reveal veritable performance of the systems. Results show that PVT-HPETC delivers better performance with 1625 W thermal energy, 81% energy efficiency and 13.22% exergy efficiency. It cuts 1.37 kg of CO2 on an hourly basis. Cascaded systems can be effective in sustaining industrial process heat requirements.

Embedded Die Packages and Modules for Power Electronics Applications

2016 ◽  
Vol 2016 (DPC) ◽  
pp. 001918-001947 ◽  
Author(s):  
Lars Boettcher ◽  
S. Karaszkiewicz ◽  
D. Manessis ◽  
A. Ostmann
Keyword(s):  
Power Electronics ◽  
Power Efficiency ◽  
High Reliability ◽  
Heat Removal ◽  
Testing Temperature ◽  
Temperature Cycling ◽  
Switching Frequency ◽  
Large Area ◽  
Power Modules ◽  
Embedded Power

Packages and modules with embedded semiconductor dies are of interest for various application fields and power classes. First packages in the lower power range are available in volume production since almost six years. Recent developments focus on medium and higher power applications raging over 500W into the kW range. Different approaches are available to realize such packages and modules. This paper will give an overview and detailed description of the latest approaches for such embedded die structures. In common of all of these approaches, is the use of laminate based die embedding, which uses standard PCB manufacturing technologies. Main differences are the used base substrate, which can still be a ceramic (DBC), Cu leadframe or high current substrate. Examples for the different methods will be given. As the main part, this paper will describe concepts, which enable significant smaller form-factor of power electronics modules, thereby allowing for lower price, high reliability, capability of direct mounting on e.g. a motor so as to form one unit with the motor housing, wide switching frequency range (for large application field) and high power efficiency. The innovative character of this packaging concept is the idea to embed the power drive components (IGBTs, MOSFETs, diode) as thinned chips into epoxy-resin layer built-up and to realize large-area interconnections on both sides by direct copper plating the dies to form a conductor structure with lowest possible electrical impedance and to achieve an optimum heat removal. In this way a thin core is formed on a large panel format which is called Embedded Power Core. The paper will specifically highlight the first results on manufacturing an embedded power discrete package as an example of an embedded power core containing a thin rectifier diode. For module realization, the power cores are interconnected to insulated metal substrates (IMS) by the use of Ag sintering interconnection technologies for the final manufacturing of Power modules. The paper will elaborate on the sintering process for Power Core/IMS interconnections, the microscopically features of the sintered interfaces, and the lateral filling of the sintering gap with epoxy prepregs. Firstly, 500W power modules were manufactured using this approach. Reliability testing results, solder reflow testing, temperature cycling test and active power cycling, will be discussed in detail.

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