Design analysis and Work load characteristics of a Micro data Center

Data centers are large-scale data storage and processing systems. It is made up of a number of servers that must be capable of handling large amount of data. As a result, data centers generate a significant quantity of heat, which must be cooled and kept at an optimal temperature to avoid overheating. To address this problem, thermal analysis of the data center is carried out using numerical methods. The CFD model consists of a micro data center, where conjugate heat transfer effects are studied. A micro data center consists of servers aligned with air gaps alternatively and cooling air is passed between the air gaps to remove heat. In the present work, the design of data center rack is made in such a way that the cold air is in close proximity to servers. The temperature and airflow in the data center are estimated using the model. The air gap is optimally designed for the cooling unit. Temperature distribution of various load configurations is studied. The objective of the study is to find a favorable loading configuration of the micro data center for various loads and effectiveness of distribution of load among the servers.

Mathematical Modelling and Operation Simulation of the Indirect Connection Scheme of the Heating Installation and of the Consumption Hot Water Preparation in an Accumulating Stage

This paper presents the mathematical model and simulation of a thermal system for heating and supplying hot water to industrial or residential consumers consisting of a heat exchanger on the heating circuit and a heat exchanger provided with an accumulation tank on the domestic hot water circuit, this scheme is generally adopted in the industrial thermal points and increasingly in module-type thermal points for residential consumers. The mathematical model is based on the mathematical equations describing this system and developed using the MATLAB - Simulink program. Thus, as a result of the simulations, we can see the evolutions in time of the water temperatures on the heating circuit and the domestic hot water circuit, as well as the quantity of heat delivered by them.

Thermochemistry

Thermochemistry explores the basic principles of energy changes in chemical reactions. Calorimetry is described as a tool to measure the quantity of heat involved in a chemical or physical change. Quantitative overviews of enthalpy and the stoichiometry of thermochemical equations are provided, including the concepts of endothermic and exothermic reactions. Standard conditions are defined to allow comparison of enthalpies of reactions and determine how the enthalpy change for any reaction can be obtained. Hess"s Law, which allows the enthalpy change of any reaction to be calculated, is discussed with illustrative examples. A presentation of bond energies and bond dissociation enthalpies is offered along with the use of bond enthalpy to estimate heats of reactions.

Which Physical Quantity Deserves the Name “Quantity of Heat”?

“What is heat?” was the title of a 1954 article by Freeman J. Dyson, published in Scientific American. Apparently, it was appropriate to ask this question at that time. The answer is given in the very first sentence of the article: heat is disordered energy. We will ask the same question again, but with a different expectation for its answer. Let us imagine that all the thermodynamic knowledge is already available: both the theory of phenomenological thermodynamics and that of statistical thermodynamics, including quantum statistics, but that the term “heat” has not yet been attributed to any of the variables of the theory. With the question “What is heat?” we now mean: which of the physical quantities deserves this name? There are several candidates: the quantities Q, H, Etherm and S. We can then formulate a desideratum, or a profile: What properties should such a measure of the quantity or amount of heat ideally have? Then, we evaluate all the candidates for their suitability. It turns out that the winner is the quantity S, which we know by the name of entropy. In the second part of the paper, we examine why entropy has not succeeded in establishing itself as a measure for the amount of heat, and we show that there is a real chance today to make up for what was missed.

Theoretical Analysis of Thin Film Evaporation in the Wicks of Loop Heat Pipes

In this paper, a thin film evaporation model that includes expressions for energy, mass and momentum conservation was established through the augmented Young-Laplace model. Based on this model, the effects of pore size and superheating on heat transfer during thin film evaporation were analyzed. The influence of the wick diameter of the loop heat pipe (LHP) on the critical heat flux of the evaporator is analyzed theoretically. The results show that pore size and superheating mainly influence evaporation through changes in the length of the transition film and intrinsic meniscus. The contribution of the transition film area is mainly reflected in the heat transfer coefficient, and the contribution of the intrinsic meniscus area is mainly apparent in the quantity of heat that is transferred. When an LHP evaporator is operating in a state of surface evaporation, a higher heat transfer coefficient can be achieved using a smaller pore size.

Fluctuating Diffusivity of RNA-Protein Particles: Analogy with Thermodynamics

A formal analogy of fluctuating diffusivity to thermodynamics is discussed for messenger RNA molecules fluorescently fused to a protein in living cells. Regarding the average value of the fluctuating diffusivity of such RNA-protein particles as the analog of the internal energy, the analogs of the quantity of heat and work are identified. The Clausius-like inequality is shown to hold for the entropy associated with diffusivity fluctuations, which plays a role analogous to the thermodynamic entropy, and the analog of the quantity of heat. The change of the statistical fluctuation distribution is also examined from a geometric perspective. The present discussions may contribute to a deeper understanding of the fluctuating diffusivity in view of the laws of thermodynamics.

Development of Standard Manufacturing Process of Joshanda

Unani System of Medicine (USM) has many safe and effective single drugs as well as compound formulations, which are commonly used in four forms solid (Hab, Qurs, Safoof, Kushta etc.); semisolid (Majoon, Laooq, Marham/Zamad etc.); liquid (Joshanda, Sharbat, Sheera, Rooh, Tila etc.) and gaseous (Bakhoor, Inkabab, Shamoom etc.). Joshanda, a preparation, in which Unani crude drugs are frequently used for treatment of common cold, catarrh, cough, associated respiratory distress and fever etc. Different Joshande are available in various Qarabadeen. In this paper a comprehensive summary has been made about various Joshande, about the drug and water ratio, yield of Joshanda and therapeutic uses of various Joshande, which is mentioned in different reference books of Unani System of Medicine. Documented evidence regarding their standard procedures of preparation/process standardization is meagre. Some important points are not specifically given, in the case of preparation of Joshandai.e quantity of heat and duration of heat. Therefore in the present study, apart from literature survey, one experimental study was also done by preparing different batches of Joshanda in different volumes (one litre, five litres and ten litres) at specific temperatures and observed the duration of heating and net volume of product left was also observed after giving suitable temperature. Keywords: Unani System of Medicine (USM), Standard Manufacturing Process (SMP), Joshanda, Decoction

Research Regarding the Improving of the Machining Parameters in the Field of Grinding Process

Grinding is one of the most important machining processes that confer the final size and surface finish for the workpiece. The paper presents a theoretical study regarding the manner in which the quantity of heat that results during grinding process is transmitted to the technological elements. The study reveals as well the influence of thermal deformations on the dimensional accuracy of the workpiece. Experimental data regarding the influence of cutting speed on the temperature in the machining zone for different cutting processes are distinguished.

Low thermal resistance packaging for high power electronics

Alumina and aluminum nitride substrates are routinely used in micro-electronic packaging where large quantity of heat needs to be dissipated, such as in LED packaging, high power electronics and laser packaging. Heat management in high power electronics or LED's is crucial for their lifespan and reliability. The ever-increasing need for higher power keeps challenging the packaging engineers to become more sophisticated in their packaging. With the availability of a 40 μm thick, high thermal conductivity ribbon alumina from Corning, the options available for packaging engineers has widened. This product has very high dielectric breakdown (~10kV at 40 μm thick), high thermal conductivity (>36 W/mK) and is rugged enough to be handled (with components attached) during packaging. These characteristics make ribbon alumina a cost-effective alternative to incumbent materials such as thick aluminum nitride, for use in high power microelectronics packaging. In this paper, high power LED and IGBT modules are modeled using commercially available code from ANSYS®. A geometry representative of typical LED packaging and IGBT packaging is constructed with Ansys Design Modeler platform and the allied meshing is done employing in-built Meshing tool in ANSYS Workbench®. We show that packaging with ~40 μm ribbon alumina delivers performance on par with or better than packaging with thicker aluminum nitride substrates.

Research on Water based Nano Fluids Effecting Thermal Performance of Heat Pipe

Heat transfer applications are most investigative area with the evolution of micro chips in electronics field; thermal equilibrium maintenance becomes a challenging task in heat pipes because of their reliability, simple structure as well as cost. Heat pipe is one of the well known heat transfer device, can transport large quantity of heat from one place to another without any additional power. Working fluid has its role on performance on the basis of its conductivity, because heat pipes have high thermal conductive nature. This review focuses on the submission of Nano-fluids in place of conventional fluids used in heat pipe. This paper reveals the researches on thermosyphons, heat pipes and oscillating heat pipes, for reduction in thermal resistance, enhancing the thermal efficiency and heat transfer coefficient of a heat pipe. Various input parameters and their ranges those affect the performance of heat pipe like heat input, angle of inclination, filling ratio, Nanoparticle material, size, shape and concentration of Nano-fluid, considered in different studies has been reviewed