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Article
Publication date: 3 May 2016

Amos Madhlopa

The purpose of this paper is to investigate a wall-integrated solar chimney for passive ventilation of a building cavity. Ventilation is required to improve the…

Abstract

Purpose

The purpose of this paper is to investigate a wall-integrated solar chimney for passive ventilation of a building cavity. Ventilation is required to improve the circulation of air in the built environment. This can be achieved through natural or forced convection. Natural circulation can be driven by renewable energy, and so it promotes sustainable exploitation of energy resources. Solar energy is one of the promising renewable energy resources.

Design/methodology/approach

The chimney was designed to face the Equator on the wall of a room which required ventilation. Mean monthly daily heating and cooling loads of the room were computed with and without a solar chimney by using hourly meteorological data from nine different weather sites at low, medium and high latitudes. The chimney was implemented with and without airflow control, and simulated by using the ESP-r software.

Findings

Results show that the solar chimney with airflow control marginally reduced the heating load in the building envelope, with a similar effect being exhibited by the chimney with uncontrolled airflow. The cooling load was reduced by the controlled airflow at all the nine sites. In contrast, the uncontrolled airflow increased the cooling load at some sites. In addition, the chimney with airflow control reduced the annual total thermal load at all the sites, while the chimney with uncontrolled airflow raised the total thermal load at some locations.

Originality/value

The performance of solar chimneys designed with and without airflow control systems has been investigated under the same prevailing meteorological conditions at a given site. Findings show that controlling airflow in a solar chimney reduces the total thermal load in the built environment. This information can be applied in different parts of the world.

Details

Journal of Engineering, Design and Technology, vol. 14 no. 2
Type: Research Article
ISSN: 1726-0531

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Article
Publication date: 7 January 2019

Adama Samake, Piotr Kocanda and Andrzej Kos

This paper aims to present an effective approach to integrated circuit (IC) throughput enhancement, called TΔT thermal control. It does not require any micro-architectural…

Abstract

Purpose

This paper aims to present an effective approach to integrated circuit (IC) throughput enhancement, called TΔT thermal control. It does not require any micro-architectural change of the IC. The only modification is the attachment of an additional temperature sensor at the heatsink boundary. TΔT control technique enables assessment of changes in the dimension of cooling conditions and quick reaction to the dynamic changes in the surrounding environment. As a result, the chip can operate flexibly while minimizing thermal violation.

Design/methodology/approach

Using additional knowledge about the surroundings, the on-chip temperature is regulated. The approach is first investigated theoretically. To validate the utilized thermal model, the measured temperature values of the designed and fabricated testing device are compared with the simulated one. The authors evaluated the impact of the additional sensor location on the reaction time (RT). Using the Spice model, further investigation helps to verify the hypothesis.

Findings

The control technique described in this paper showed that the temperature of the chip can be regulated using an additional knowledge of the surrounding environment. It has also been demonstrated that the attachment of an additional temperature sensor close to the cooled surface of the package enables TΔT thermal control technique to react faster (rapid powering up/down of the IC). Therefore, this lowers the risk of shutdown while keeping the temperature close to the thermal limit (the maximal temperature of the chip) for a significant period. The simulation results showed that a higher ambient temperature leads to diminution of the interval in which the on-chip temperature stays almost constant when TΔT technique is used (time shift).

Originality/value

In this study, a new thermal throttling technique that uses the full physical ability of the chip operating under thermal constraint has been evaluated.

Details

Microelectronics International, vol. 36 no. 1
Type: Research Article
ISSN: 1356-5362

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Article
Publication date: 1 April 2005

Tsung‐Nan Tsai and Taho Yang

A neural‐network‐based predictive model is proposed to model the second‐side thermal profile reflow process in surface mount assembly with a view to facilitating the oven…

Abstract

Purpose

A neural‐network‐based predictive model is proposed to model the second‐side thermal profile reflow process in surface mount assembly with a view to facilitating the oven set‐up procedure and improving production yield.

Design/methodology/approach

This study performs a 38−4 fractional factorial experimental twice to collect the thermal‐profile data from a second‐side board. The first experiment has components on the second side only, while the second experiment also has additional components on the primary side. A back‐propagation neural network (BPN) is then used to model the relationship between control variables and thermal‐profile measures.

Findings

Empirical results illustrate the efficiency and effectiveness of the proposed BPN in solving the second‐side thermal‐profile prediction and control problem.

Originality/value

There is no study dedicated to the investigation of the second‐side thermal‐profile variance with and without the presence of primary‐side components. The study suggests that a variant oven‐setting strategy for the second‐side reflow process is important to ensure reflow‐soldering quality.

Details

Journal of Manufacturing Technology Management, vol. 16 no. 3
Type: Research Article
ISSN: 1741-038X

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Article
Publication date: 1 December 2012

Mike Adebamowo and Adetokunbo O. Ilesanmi

Buildings have a considerable impact on the environment being responsible for a substantial proportion of global energy consumption, thus contributing significantly to the…

Abstract

Buildings have a considerable impact on the environment being responsible for a substantial proportion of global energy consumption, thus contributing significantly to the anthropogenic CO2 emissions, which evidence suggests is the main cause of climate change. Mitigation and adaptation measures are required to tackle the challenges of climate change. Adaptive measures – structural and behavioural strategies – are the focus of this paper. Structural strategies include flexible and adaptive structural systems; while behavioural strategies cover the spatial, personal, and psychological control measures which may influence the design and operations of buildings. The study explores the adaptive thermal comfort of occupants and examines the design strategies for adapting buildings to climate change in the tropical context, with a view to determine the effectiveness of these strategies as observed in the case study. The study was conducted during the rainy and dry seasons in Abeokuta, Ogun State, Nigeria, located in a warm humid climate zone.

The Institute of Venture Design student hostel was used as case-study to conduct the survey on a sample of 40 respondents by means of structured questionnaire. The respondents' thermal sensation and access to thermal controls were determined, and their thermal sensation and thermal adaptability in both seasons comparatively analyzed. Indoor environmental parameters including air temperature, mean radiant temperature, relative humidity and air velocity were also measured. The data were analyzed using relevant descriptive and inferential statistics. The study discussed the effectiveness of design strategies available for building adaptation in an era of climate change within the warm humid environment, concluding on the need for greater synergy between the techno-structural and socio-behavioural dimensions of building adaptation.

Details

Open House International, vol. 37 no. 4
Type: Research Article
ISSN: 0168-2601

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Article
Publication date: 1 December 2005

Daniel Jean, W. Jack Lackey and Chad E. Duty

To describe the thermal imaging control system used to deposit lines of graphite in a laser chemical vapor deposition (LCVD) system.

Abstract

Purpose

To describe the thermal imaging control system used to deposit lines of graphite in a laser chemical vapor deposition (LCVD) system.

Design/methodology/approach

A thermal imaging‐based control system is applied to the LCVD process to deposit layered carbon lines of uniform height and width. A 100 W CO2 laser focused to a 200 μm diameter spot size is used to provide the heat source for the carbon deposition. A high resolution thermal imaging camera is used to monitor and control the average deposition temperature.

Findings

Carbon lines are grown with heights of 250 μm and widths of 170 μm consisting of 20 layers. Laser spot temperatures are in excess of 2,170°C, and the total pressure used is 1 atm with a 75 percent methane concentration and the remainder hydrogen. The length of the lines is 3.3 mm, and the scan speed is 5 mm/min. The volumetric deposition rate is 0.648 mm3/h.

Research limitations/implications

The temperature process control resulted in uniform geometry at the center of the lines, but it was not as effective at the ends of the lines where the geometry was more complex.

Originality/value

Introduces a control technique for uniform line deposition for the LCVD process, which represents a core building block for complex geometries. The establishment of basic control algorithms will enable LCVD to realize the potential for rapid prototyping of metals and ceramics with sub‐millimeter feature sizes.

Details

Assembly Automation, vol. 25 no. 4
Type: Research Article
ISSN: 0144-5154

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Article
Publication date: 30 May 2008

Sui‐Pheng Low, Junying Liu and John Lim

Where buildability is concerned, the six total building performance (TBP) mandates are seldom taken into consideration.. The purpose of this paper is to examine the…

Abstract

Purpose

Where buildability is concerned, the six total building performance (TBP) mandates are seldom taken into consideration.. The purpose of this paper is to examine the relationship between buildability and the two TBP mandates of thermal performance and building integrity performance.

Design/methodology/approach

A real life case study of a worker dormitories building project was used as the base model for analysis. A breakdown of the buildability scores for the project was first noted. Thereafter, the TBP guidelines relating to thermal performance and building integrity performance were incorporated into the base model and the buildability scores were recomputed.

Findings

Following the thermal performance guidelines, a negative relationship with buildability was observed. However, a positive result was established between the building integrity performance guidelines and buildability. The different relationships occurred due to the different aspects of the base model that needed to be changed to conform to the guidelines for both mandates.

Practical implications

It appears that the incorporation of guidelines for any one of the six TBP mandates will yield different results depending on the situation. This was the case for both thermal performance and building integrity performance in the present study.

Originality/value

The paper establishes the relationship between the TBP mandates of thermal performance, building integrity performance and buildability for the first time, which is beneficial to building designers.

Details

Structural Survey, vol. 26 no. 2
Type: Research Article
ISSN: 0263-080X

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Article
Publication date: 4 November 2014

Meshack O. Efeoma and Ola Uduku

The purpose of this paper is to adduce the most appropriate thermal comfort assessment method for determining human thermal comfort and energy efficient temperature control

Abstract

Purpose

The purpose of this paper is to adduce the most appropriate thermal comfort assessment method for determining human thermal comfort and energy efficient temperature control in office buildings in tropical West Africa.

Design/methodology/approach

This paper examines the Adaptive Thermal Comfort Standard, from its research evolution to its contemporary use as an environmental design assessment Standard. It compares the adaptive component of ASHRAE Standard 55 and the European CEN/EN 15251. It begins by reviewing relevant literature and then produces a comparative analysis of the two standards, before suggesting the most appropriate Adaptive Thermal Comfort Standard for use in assessing conditions in tropical climate conditions. The suggested Standard was then used to analyse data collected from the author's pilot research into thermal conditions, in five office buildings situated in the city of Enugu, South Eastern Nigeria.

Findings

The paper provides insight as to why the ASHRAE adaptive model is more suitable for thermal comfort assessment of office buildings in the tropical West African climate. This was demonstrated by using the ASHRAE Thermal Comfort Standard to assess comfort conditions from pilot research study data collected on Nigerian office buildings by the author.

Originality/value

The paper compares the adaptive component of ASHRAE Standard 55 with CEN/EN 15251, and their different benefits for use in tropical climates. It suggested the need for further research studies and application of the ASHRAE Adaptive Thermal Comfort Standard in the tropical West African climate.

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Article
Publication date: 12 August 2020

Ahmad Soleymani and Mehran Nosratollahi

The purpose of this paper is to simulate the thermal performance of fluidic momentum controller (FMC) actuators in two case, with and without thermal distribution system…

Abstract

Purpose

The purpose of this paper is to simulate the thermal performance of fluidic momentum controller (FMC) actuators in two case, with and without thermal distribution system on a three-axis configuration of FMC actuators to an orbital period of satellite. The results show the effectiveness of using a storage with FMC actuators.

Design/methodology/approach

One of the challenges during a satellite’s orbital mission is unpredictable external temperature perturbations. This system used as a collaborative thermal subsystem for microsatellite temperature passive control. The operating principles of the system are that each fluid rings are used in a microsatellite surface with pumps to stabilize the satellite. All fluid rings are connected to the satellite thermal distribution system (storage).

Findings

Simulation results show that with using of thermal distribution system, damping of satellite different surfaces temperature is rapidly possible to the event of thermal disturbances.

Practical implications

Numerical simulation is obtained by ANSYS Fluent software and pressure-velocity coupling is SIMPLE method and spatial discretization is second order accurate and first order in time, viscous model is k-e. In this regard, a solver algorithm is also developed.

Originality/value

In space research fields about FMC application as actuators to satellite system design, main goal is to research about role of this system to attitude and determination control system (ADCS) of satellites, and no study is performed on its role to satellite temperature damping. This study is exclusively simulated thermal distribution system (includes a storage and its connections) of a microsatellite equipped with FMC actuators. The idea of using a storage for FMC actuators is the innovative step of this research.

Details

Aircraft Engineering and Aerospace Technology, vol. 92 no. 10
Type: Research Article
ISSN: 1748-8842

Keywords

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Article
Publication date: 16 April 2018

Sergey Shevtsov, Igor V. Zhilyaev, Ilya Tarasov, Jiing-Kae Wu and Natalia G. Snezhina

The purpose of this paper is to develop the multi-objective optimization approach and its numerical implementation to synthesise the model-base control for the part curing…

Abstract

Purpose

The purpose of this paper is to develop the multi-objective optimization approach and its numerical implementation to synthesise the model-base control for the part curing at autoclave processing, which supplies the stability and uniformity of the structure and mechanical properties of the material within the cured composite part.

Design/methodology/approach

The approach includes conversion of the cured part and mold geometry from their computer-aided design (CAD) to computer-aided engineering (CAE) representation, a finite element (FE) formulation of the coupled forward heat transfer/thermal kinetic problem with the parameters of prepreg, which should be determined by the thermal analysis, and, finally, a mapping of the area of 4D design space (thermal control parameters) to 2D objective space, whose coordinates are the maximum deviations of degree of cure and temperature within the cured part calculated at each call of the FE model.

Findings

The present modeling and optimization approach to the cure process control of the prepreg with thermosetting resin, as well as the means of visualizing optimization results, allow providing insight into complex curing phenomena, estimating the best achievable quality indicators of manufactured composite parts, finding satisfactory parameters of the control law and deciding considering all manufacturing constraints.

Research limitations/implications

The research can be effectively used to optimize the cure process control for a wide class of polymeric composite parts, even with a complex geometry, but it requires the exact conversion of the geometry of the modeled part from the CAD to CAE environment, which implies the need for excluding all topological imperfections of original CAD model to eliminate the possible formation of void elements and other reasons that do not allow the correct FE meshing. Because thermal, rheological and kinetics parameters, which include the governing equations of cure process, depend on the reinforcing fibers, and especially on the resin properties, the thermal testing for the new modeled prepreg needs to be performed.

Practical implications

Computer implementation of the proposed approach and numerical method for model-based optimal control synthesis for composite part cure process can be used in aircraft, rotorcraft, ship and automotive technologies at the design of manufacturing process of the large composite parts with complex shape.

Social implications

This will allow much better quality for large-scale composite parts, excluding very expensive, time-, energy- and material-consuming multiple cure process testing.

Originality/value

This is first time the problem of optimal control synthesis for curing the large-scale composite parts of complex shape was solved.

Details

Engineering Computations, vol. 35 no. 2
Type: Research Article
ISSN: 0264-4401

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Article
Publication date: 10 August 2018

Xibing Li, Weixiang Li, Xueyong Chen, Ming Li, Huayun Chen and Xin Yue

The purpose of this paper is to examine the effect of application of a heat pipe in an aspect of hydrostatic thrust bearings on thermal balance and deformation and the…

Abstract

Purpose

The purpose of this paper is to examine the effect of application of a heat pipe in an aspect of hydrostatic thrust bearings on thermal balance and deformation and the role of this application in increasing the rotating speed of a workbench.

Design/methodology/approach

Numerical simulations of oil film temperature field, the temperature field and thermal deformation of the bearing’s workbench and base were performed by finite element analysis (FEA) software for both the traditional hydrostatic thrust bearings and the heat pipe ones.

Findings

Oil pad and workbench of the hydrostatic thrust bearings are fabricated with a heat pipe cooling structure, which can take away most of the heat generated by shearing of the oil film, control the temperature rise and thermal deformation of the hydrostatic thrust bearing effectively, avoid the dry friction phenomenon and finally improve the processing quality of equipment.

Originality/value

The heat pipe hydrostatic thrust bearings could control the temperature rise and thermal deformation of the hydrostatic thrust bearing effectively, avoid the dry friction phenomenon and improve the processing quality of equipment.

Details

Industrial Lubrication and Tribology, vol. 70 no. 7
Type: Research Article
ISSN: 0036-8792

Keywords

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