Digital Commons Network^™

Ventilative Cooling Through Automated Window Opening Control Systems To Address Thermal Discomfort Risk During The Summer Period: Framework, Simulation And Parametric Analysis, Theofanis Psomas, Massimo Fiorentini, Georgios Kokogiannakis, Per K. Heiselberg

Faculty of Engineering and Information Sciences - Papers: Part B

Automated window opening control systems with integrated ventilative cooling strategies may significantly diminish the thermal discomfort and overheating risk of dwellings during cooling periods in temperate climates. One of the challenges with demonstrating the benefits of the systems is the lack of building performance simulation (BPS) tools which may represent precisely how actual algorithms are applied.

The study supported herein aims to present a framework of how to simulate an advanced ventilative cooling algorithm of a window system on coupled BPS environments (ESP-r and BCVTB tools). Parametric analysis has been conducted to verify specific operational functions of the system. The …

Linear Regression Models For Prediction Of Annual Heating And Cooling Demand In Representative Australian Residential Dwellings, Navid Aghdaei, Georgios Kokogiannakis, Daniel J. Daly, Timothy J. Mccarthy

Faculty of Engineering and Information Sciences - Papers: Part B

This paper presents the development methodology of linear regression models that were developed for the prediction of annual thermal loads in representative residential buildings across three major climates in New South Wales, Australia, and the assessment of the impact of building envelope upgrades. A differential sensitivity analysis was undertaken for sixteen building envelope parameters, with six parameters being identified as significant. These six parameters were then explored using EnergyPlus simulation, and a number of linear regression models developed from the simulation outputs. Random values for design parameters were generated, and the results of EnergyPlus simulations using these parameters were used …

Development Of Intermediate Cooling Technology And Its Control For Two-Stand Plate Rolling, Fei Zhang, Wei Yu, Tao Liu

Faculty of Engineering and Information Sciences - Papers: Part A

In a plate rolling production line, thermomechanically controlled processing is critical for plate quality. In this paper, a set of intermediate cooling equipment of a two-stand plate mill with super density nozzles, medium pressure, and small flow is developed. Based on a simplified dynamic model, a cooling control scheme with combined feedforward, feedback, and adaptive algorithms is put forward. The new controlled rolling process and the highly efficient control system improve the controlled rolling efficiency by an average of 17.66%. The proposed intermediate cooling system can also effectively inhibit the growth of austenite grain, improve the impact toughness and yield …

Development Of A Novel Phase Change Material Emulsion For Cooling Systems, Jingjing Shao, Jo Darkwa, Georgios Kokogiannakis

Faculty of Engineering and Information Sciences - Papers: Part A

In this paper, a novel phase change material emulsion (PCE-10) consisting of an organic PCM (RT10) and water has been developed. Its thermophysical properties such as heat of fusion, viscosity and sub-cooling temperature have been established. The chemical stability during both storage and discharge periods have also been evaluated. The results indicate low sub-cooling temperature and relatively long period of stability without any sign of segregation but the viscosity was found to be much higher than that of water.Further improvement and experimental studies into its flow characteristics are therefore being encouraged.

The Effect Of Nb On The Continuous Cooling Transformation Curves Of Ultra-Thin Strip Castrip© Steels, Kristin R. Carpenter, Chris R. Killmore

Faculty of Engineering and Information Sciences - Papers: Part A

The effect of Nb on the hardenability of ultra-thin cast strip (UCS) steels produced via the unique regime of rapid solidification, large austenite grain size, and inclusion engineering of the CASTRIP^© process was investigated. Continuous cooling transformation (CCT) diagrams were constructed for 0, 0.014, 0.024, 0.04, 0.06 and 0.08 wt% Nb containing UCS steels. Phase nomenclature for the identification of lower transformation product in low carbon steels was reviewed. Even a small addition of 0.014 wt% Nb showed a potent effect on hardenability, shifting the ferrite C-curve to the right and expanding the bainitic ferrite and acicular ferrite phase …

The Optimisation Of The Secondary Cooling Water Distribution With Improved Genetic Algorithm In Continuous Casting Of Steels, Yu-Chun Zhai, Ying Li, Beiyue Ma, C Yan, Zhengyi Jiang

Faculty of Engineering and Information Sciences - Papers: Part A

An improved genetic algorithm is presented for the water consumption of the secondary cooling zone based on the heat transfer model of the off-line bloom caster. This study is to control the existing cooling systems and the steel casting practises in order to produce steel with best possible quality. The fitness function of improved genetic algorithm is founded according to the metallurgical criteria. This algorithm coupled with heat transfer model and metallurgical criteria, added dynamic coding method and self-adapting mutation on the original genetic algorithm can increase water distribution adaptively and improve the process efficiency. The simulation results of T91 …

Integrated Dehumidification And Downdraft Evaporative Cooling System For A Hot-Humid Climate, Sriraj Gokarakonda, Georgios Kokogiannakis

Faculty of Engineering and Information Sciences - Papers: Part A

Unlike in hot-dry climates, in hot-humid climates evaporative cooling techniques are not readily suitable for space cooling. In order to effectively use evaporative cooling in hot-humid climates, dehumidification of ambient air is necessary before it passes over an evaporative medium for cooling. The present study explores the combined process of dehumidification and evaporation and its effect on thermal comfort in a typical small residential building located in a hot humid climate. A novel system has been investigated with the combination of an Earth Tube Ventilation (ETV) (for pre-cooling of air), a rotary wheel desiccant dehumidifier (for dehumidification) along with a …

Effect Of Cooling Rate On Oxidation Behaviour Of Microalloyed Steel, Xianglong Yu, Zhengyi Jiang, Jingwei Zhao, Dongbin Wei, Cunlong Zhou

Faculty of Engineering and Information Sciences - Papers: Part A

Oxidation characteristics of a microalloyed low carbon steel were investigated by a hot rolling mill combined with acceleration cooling system over the cooling rate range from 20 to 70°C/s. The effects of cooling rate after hot rolling on microstructure and phase composition of oxide scale were examined. The results showed that the increase of the cooling rate has a significant influence on the decrease of the grain size and surface roughness of oxide scale. A higher cooling rate promotes the formation of retain wustite and primary magnetite precipitation while suppression of eutectoid α-iron precipitates. This provides the possibility to enhance …

Work Hardening Behaviors Of A Low Carbon Nb-Microalloyed Si-Mn Quenching-Partitioning Steel With Different Cooling Styles After Partitioning, Jun Zhang, Hua Ding, Chao Wang, Jingwei Zhao, Ting Ding

Faculty of Engineering and Information Sciences - Papers: Part A

In this paper, the strain hardening behaviors of a low carbon Nb-microalloyed Si–Mn quenching–partitioning (Q–P) steel were investigated. The microstructures were analyzed by the scanning electron microscope (SEM) and transmission electron microscope (TEM). Mechanical tests were used to evaluate the room temperature tensile properties of the steel. The work hardening behaviors of the tested specimens were analyzed using the Hollomon approach. The results showed that a two-stage work hardening behavior was observed during deformation processes. In the first stage, for the quenched samples, martensite deforms plastically and the hardening exponent decreased. For the air-cooled samples, however, the carbide-free ferrite deforms …

The Effect Of Cooling Rates On The Microstructure And Mechanical Properties Of Thermo-Mechanically Processed Ti-Al-Mo-V-Cr-Fe Alloys, Mansur Ahmed, Dmytro G. Savvakin, Orest M. Ivasishin, Elena V. Pereloma

Faculty of Engineering and Information Sciences - Papers: Part A

Two near-β titanium alloys, Ti–5Al–5Mo–5V–1Cr–1Fe and a modified one containing 2 wt% Cr (Ti–5Al–5Mo–5V–2Cr–1Fe) were produced from Ti hydride precursor powders via the cost-effective blended elemental powder metallurgy technique. The effects of two cooling rates (10 K s−1 and 1 K s−1) during thermo-mechanical processing on the microstructure and mechanical properties were investigated using X-ray diffraction and scanning electron microscopy. X-ray line profile analysis revealed that dislocation densities and microstrain in β-Ti phase are higher than in α-Ti phase for all cases. In both alloys, slower cooling results in an increase in α volume fraction and promotes morphology of continuous …

Effects Of Tungsten On Continuous Cooling Transformation Characteristics Of Microalloyed Steels, Jingwei Zhao, Zhengyi Jiang, Ji Soo Kim, Chong Soo Lee

Faculty of Engineering and Information Sciences - Papers: Part A

Continuous cooling transformation (CCT) characteristics of microalloyed steels with different tungsten (W) contents (0, 0.1 and 1. wt.%) were investigated to obtain the necessary information for heat treatment of these steels. The effects of W addition on the sizes of prior austenite grains and precipitates were analysed. CCT diagrams were obtained by varying the cooling rates from 0.1 to 120. °C/s. Transformation characteristics were determined by using dilatometer test, microscopic observation and hardness measurement. The results showed that W had a positive effect on the refinement of prior austenite grains and precipitates. The CCT diagrams exhibited that the ranges of …

Distortion Behavior Of A Heavy Hydro Turbine Blade Casting During Forced Air Cooling In Normalizing Treatment Process, Hailiang Yu, Jinwu Kang, T J. Wang, J A. Ma, Y Y. Hu, Tianyou Huang, S B. Wang, Y Wu, C C. Zhang, Yan-Tao Dai, P Li

Faculty of Engineering and Information Sciences - Papers: Part A

Distortion behavior of blade castings in heat treatment process determines their geometrical accuracy, and improper control of it may result in additional repair, shape righting, or even rejection. This article presents a novel approach for discovering the distortion behavior of heavy blade castings during heat treatment process in production. Real-time measurements of distortion and temperature field of a heavy hydro turbine blade casting weighted 17 ton during forced air cooling in normalizing treatment process were carried out by using deformation measurement instruments and an infrared thermal imaging camera. The distortion processes of the typical locations of blade and the temperature …

Thermal, Microstructural And Mechanical Coupling Analysis Model For Flatness Change Prediction During Run-Out Table Cooling In Hot Strip Rolling, Xiao-Dong Wang, Fei Li, Zheng-Yi Jiang

Faculty of Engineering and Information Sciences - Papers: Part A

Non-uniformity of temperature distribution across strip width direction is the ultimate reason why the flatness defect occurs on the strip after cooling process although the strip is flat at the exit of finishing mill. One thermal, microstructural and mechanical coupling analysis model for predicting flatness change of steel strip during the run-out table cooling process was established using ABAQUS finite element software. K Esaka phase transformation kinetics model was employed to calculate the phase transformation, and coupled with temperature calculation using the user subroutine program HETVAL. Elasto-plasticity constitutive equations of steel material, in which conventional elastic and plastic strains, thermal …

On The Soft X-Ray Spectrum Of Cooling Flows, A C. Fabian, R F. Mushotzky, Paul E. J Nulsen, J R. Peterson

Faculty of Engineering and Information Sciences - Papers: Part A

Strong evidence for cooling flows has been found in low-resolution X-ray imaging and spectra of many clusters of galaxies. However, high-resolution X-ray spectra of several clusters from the Reflection Grating Spectrometer on XMM-Newton now show a soft X-ray spectrum inconsistent with a simple cooling flow. The main problem is a lack of the emission lines expected from gas cooling below 1–2 keV. Lines from gas at about 2–3 keV are observed, even in a high-temperature cluster such as A1835, indicating that gas is cooling down to about 2–3 keV, but is not found at lower temperatures. Here we discuss several …

Asca And Rosat Observations Of Nearby Cluster Cooling Flows, S W. Allen, A C. Fabian, R M. Johnstone, K A. Arnaud, Paul E J Nulsen

Faculty of Engineering and Information Sciences - Papers: Part A

We present a detailed analysis of the X-ray properties of the cooling flows in a sample of nearby, X-ray-bright clusters of galaxies using high-quality ASCA spectra and ROSAT X-ray images. We demonstrate the need for multiphase models to consistently explain the spectral and imaging X-ray data for the clusters. The mass deposition rates of the cooling flows, independently determined from the ASCA spectra and ROSAT images, exhibit reasonable agreement. We confirm the presence of intrinsic X-ray absorption in the clusters using a variety of spectral models. We also report detections of 100-μm infrared emission, spatially coincident with the cooling flows, …