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Author

Yunho Hwang

Other affiliations: Sanyo, LG Electronics
Bio: Yunho Hwang is an academic researcher from University of Maryland, College Park. The author has contributed to research in topics: Air conditioning & Heat exchanger. The author has an hindex of 42, co-authored 248 publications receiving 6272 citations. Previous affiliations of Yunho Hwang include Sanyo & LG Electronics.


Papers
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Journal ArticleDOI
TL;DR: In this article, the authors demonstrate that elastocaloric cooling (EC), a type of solid-state cooling mechanism based on the latent heat of reversible martensitic transformation, can have the coefficient of performance as high as ≈11, with a directly measured ΔT of 17 C.
Abstract: Vapor compression (VC) is by far the most dominant technology for meeting all cooling and refrigeration needs around the world. It is a mature technology with the efficiency of modern compressors approaching the theoretical limit, but its environmental footprint remains a global problem. VC refrigerants such as hydrochloroflurocarbons (HCFCs) and hydrofluorocarbons (HFCs) are a significant source of green house gas emissions, and their global warming potential (GWP) is as high as 1000 times that of CO2 [Buildings Energy Data Book (Building Technologies Program, Department of Energy, 2009)]. There is an urgent need to develop an alternative high-efficiency cooling technology that is affordable and environmentally friendly [A. D. Little, Report For Office of Building Technology State and Community Programs, Department of Energy, 2001]. Here, we demonstrate that elastocaloric cooling (EC), a type of solid-state cooling mechanism based on the latent heat of reversible martensitic transformation, can have the coefficient of performance as high as ≈11, with a directly measured ΔT of 17 °C. The solid-state refrigerant of EC completely eliminates the use of any GWP refrigerants including HCFCs/HFCs.

378 citations

Journal ArticleDOI
TL;DR: In this paper, the authors reviewed the recent development of available cold storage materials for air conditioning application, including water and ice, salt hydrates and eutectics, paraffin waxes and fatty acids, refrigerant hydrate, microencapsulated phase change materials/slurries and phase change emulsions.
Abstract: This paper reviews the recent development of available cold storage materials for air conditioning application. According to the type of storage media and the way a storage medium is used, water and ice, salt hydrates and eutectics, paraffin waxes and fatty acids, refrigerant hydrates, microencapsulated phase change materials/slurries and phase change emulsions are separately introduced as suitable energy storage or secondary loop media. Water storage and static ice storage, which are already well-established technologies, have little need for further study. Dynamic ice slurry application is discussed especially for its generation method, relating to the efficiency and reliability of converting water or aqueous solution to ice crystals or ice slurry. Thermal and physicochemical properties of different phase change materials have been summarized including latent heat, thermal conductivity, phase separation, supercooling, and corrosion. Moreover, corresponding solutions for issues of different materials are also discussed. Thermal and hydraulic characteristics of phase change slurries (mainly about clathrate slurries, microencapsulated phase change slurries, and phase change emulsions) are discussed and summarized. In addition, the principle of the sorption cold storage is described and different kinds of working pairs are introduced. Relevant perspectives for commercialization of storage materials are discussed.

276 citations

Journal ArticleDOI
TL;DR: In this article, a comprehensive review of key issues related to achieving a successful elastocaloric cooling system is presented, where the basic and advanced thermodynamic cycles are presented based on analogy from other solid-state cooling technologies.
Abstract: Elastocaloric cooling is a new alternative solid-state cooling technology undergoing early stage research and development. This study presents a comprehensive review of key issues related to achieving a successful elastocaloric cooling system. Fundamentals in elastocaloric materials are reviewed. The basic and advanced thermodynamic cycles are presented based on analogy from other solid-state cooling technologies. System integration issues are discussed to characterize the next generation elastocaloric cooling prototype. Knowledge acquired from the elastocaloric heat engines is provided as the basis for the design of cooling system configuration. Commercially available drivers enabling proper compression and tension are also presented. A few performance assessment indices are proposed and discussed as guidelines for design and evaluation of future elastocaloric cooling system. A brief summary of the up-to-date elastocaloric cooling prototypes is presented as well.

229 citations

Journal ArticleDOI
01 Mar 2013-Energy
TL;DR: In this paper, the authors reviewed the recent development of available cold storage materials for subzero applications, and introduced phase change material (PCM) storage and sorption storage separately.

216 citations

Journal ArticleDOI
TL;DR: In this paper, a genetic algorithm (GA) from Matlab optimization toolbox was used to optimize a propane pre-cooled mixed refrigerant (C3-MR) LNG plant that was originally designed by Mortazavi et al.

211 citations


Cited by
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Christopher M. Bishop1
01 Jan 2006
TL;DR: Probability distributions of linear models for regression and classification are given in this article, along with a discussion of combining models and combining models in the context of machine learning and classification.
Abstract: Probability Distributions.- Linear Models for Regression.- Linear Models for Classification.- Neural Networks.- Kernel Methods.- Sparse Kernel Machines.- Graphical Models.- Mixture Models and EM.- Approximate Inference.- Sampling Methods.- Continuous Latent Variables.- Sequential Data.- Combining Models.

10,141 citations

01 Jan 2007

1,932 citations

Journal ArticleDOI
TL;DR: In this article, the status and current trends of energy consumption, CO2 emissions and energy policies in the residential sector, both globally and in those ten countries, were reviewed, and it was found that global residential energy consumption grew by 14% from 2000 to 2011, where population, urbanization and economic growth have been the main driving factors.
Abstract: Climate change and global warming as the main human societies’ threats are fundamentally associated with energy consumption and GHG emissions. The residential sector, representing 27% and 17% of global energy consumption and CO2 emissions, respectively, has a considerable role to mitigate global climate change. Ten countries, including China, the US, India, Russia, Japan, Germany, South Korea, Canada, Iran, and the UK, account for two-thirds of global CO2 emissions. Thus, these countries’ residential energy consumption and GHG emissions have direct, significant effects on the world environment. The aim of this paper is to review the status and current trends of energy consumption, CO2 emissions and energy policies in the residential sector, both globally and in those ten countries. It was found that global residential energy consumption grew by 14% from 2000 to 2011. Most of this increase has occurred in developing countries, where population, urbanization and economic growth have been the main driving factors. Among the ten studied countries, all of the developed ones have shown a promising trend of reduction in CO2 emissions, apart from the US and Japan, which showed a 4% rise. Globally, the residential energy market is dominated by traditional biomass (40% of the total) followed by electricity (21%) and natural gas (20%), but the total proportion of fossil fuels has decreased over the past decade. Energy policy plays a significant role in controlling energy consumption. Different energy policies, such as building energy codes, incentives, energy labels have been employed by countries. Those policies can be successful if they are enhanced by making them mandatory, targeting net-zero energy building, and increasing public awareness about new technologies. However, developing countries, such as China, India and Iran, still encounter with considerable growth in GHG emissions and energy consumption, which are mostly related to the absence of strong, efficient policy.

1,212 citations

Journal ArticleDOI
TL;DR: The resulting magnetocaloric, electrocaloric and mechanocaloric effects are compared here in terms of history, experimental method, performance and prospective cooling applications.
Abstract: A magnetically, electrically or mechanically responsive material can undergo significant thermal changes near a ferroic phase transition when its order parameter is modified by the conjugate applied field. The resulting magnetocaloric, electrocaloric and mechanocaloric (elastocaloric or barocaloric) effects are compared here in terms of history, experimental method, performance and prospective cooling applications.

1,101 citations

01 Jan 1987

991 citations