Papers by Siddharth Bhopte
Numerical Study on the Reduction of Recirculation Using Sealed Cold Aisles and its Effect on the Efficiency of the Cooling Infrastructure
ASME 2011 Pacific Rim Technical Conference and Exhibition on Packaging and Integration of Electronic and Photonic Systems, MEMS and NEMS: Volume 2, 2011
The increase in computing performance of electronic equipment is causing higher power consumption... more The increase in computing performance of electronic equipment is causing higher power consumption and in turn higher heat dissipation. On the larger scale, data centers that house hundreds of these individual electronic equipment are foreseeing an inevitable increase in heat dissipation on a facility level. The cooling cost of these rooms is becoming a major challenge, where a specified inlet temperature must not be exceeded in order to insure the safe and reliable operation of the electronic equipment. Most of the data centers in use today adopt the hot aisle-cold aisle configuration, where air is supplied through a plenum. The major problem with this configuration is the mixing of cold supply air from the tiles with hot exhaust air from the servers. This affects the efficiency of the cooling infrastructure and in turn affects the cost of operation. This study concentrates on the idea of sealing the cold aisle. Completely sealing the cold aisle is not practical due to pressure and ...
Effect of Thermal Characteristics of Electronic Enclosures on Dynamic Data Center Performance
Volume 4: Electronics and Photonics, 2010
Data centers are the facilities that house large number of computer servers that dissipate high p... more Data centers are the facilities that house large number of computer servers that dissipate high power. Considering the dynamics of the data centers, their efficient thermal management is a big challenge that needs to be addressed. Computational analysis using a CFD code is very useful technique that helps the engineer to understand and solve the data center cooling problem. Several ongoing numerical modeling research efforts assume the computer room air conditioning (CRAC) units as fixed flow devices with constant temperature boundary condition. In reality, CRAC supply temperature is governed by the thermal characteristic curve, as specified by vendor. In this paper, study is presented by incorporating the CRAC thermal characteristic curve in the numerical model. Case studies are presented to show how the segregated high and low powered clusters in a data center may affect the supply temperatures from the CRAC in their vicinity. Another concern that is crucial in analyzing data cent...
Numerical and experimental study of the effect of thermocouple wire attachment on thermal characterization of a high performance flipchip package
Intersociety Conference on Thermal and Thermomechanical Phenomena in Electronic Systems, 2010
Thermal resistance of an electronic package is a measure of the package's ability to transfer... more Thermal resistance of an electronic package is a measure of the package's ability to transfer the heat generated by the chip to the printed wiring board (PWB) or to the ambient. For a high performance flip-chip package, the primary heat transfer path for most applications is through a heat sink or cold plate attached to the package lid. Hence, a
Numerical modeling of data center with transient boundary conditions
2010 12th IEEE Intersociety Conference on Thermal and Thermomechanical Phenomena in Electronic Systems, 2010
NUMERICAL MODELING OF DATA CENTER WITH TRANSIENT BOUNDARY CONDITIONS Srujan Gondipalli1, Mahmoud ... more NUMERICAL MODELING OF DATA CENTER WITH TRANSIENT BOUNDARY CONDITIONS Srujan Gondipalli1, Mahmoud Ibrahim1, Siddharth Bhopte1, Bahgat Sammakia1, Bruce Murray1, Kanad Ghose1, Madhusudan K. Iyengar2 & Roger Schmidt2 ^tate University of ...
Numerical modeling approach to dynamic data center cooling
2010 12th IEEE Intersociety Conference on Thermal and Thermomechanical Phenomena in Electronic Systems, 2010
ABSTRACT Data centers are facilities that house large numbers of computer servers that dissipate ... more ABSTRACT Data centers are facilities that house large numbers of computer servers that dissipate high power. Due to varying operational loads their efficient thermal management is a big challenge that needs to be addressed. Computational modeling using a CFD code is a very useful ...
Optimization of Cold Aisle Isolation Designs for a Data Center With Roofs and Doors Using Slits
ASME 2009 InterPACK Conference, Volume 2, 2009
Data centers are facilities that house large numbers of computer servers that typically dissipate... more Data centers are facilities that house large numbers of computer servers that typically dissipate high power. With the rapid increase in the heat flux of such systems, their thermal management represents an economic and environmental challenge that needs to be addressed [2]. Considering the trends of increasing heat loads and heat fluxes, the focus for users is in providing adequate airflow through the equipment at a temperature that meets the manufacturers’ requirements. Data centers house IT equipment in racks typically arranged in rows which face one another. Alternating cold and hot aisles are formed and this pattern is repeated across the data center. This approach helps to separate cold and hot air streams; but this does not always suffice in the separation of cold and hot air. The mixing of hot rack exhaust air with cold supply air, short-circuiting of cold air to the coolers and the recirculation of hot air to racks’ inlet are the common phenomena that lead to thermal ineffi...
Numerical Modeling of Data Center Clusters
Energy Efficient Thermal Management of Data Centers, 2012
This chapter deals with the numerical modeling of data centers. The chapter presents an overview ... more This chapter deals with the numerical modeling of data centers. The chapter presents an overview of the fundamental equations governing the conservation of mass, energy, and momentum, with an emphasis on the most widely used numerical approaches used for discretizing the equations and solving them. The specific simplifications and assumptions that are typically used in modeling data centers are reviewed. Turbulent modeling is covered in some detail, with an emphasis on the suitability of different models for data centers. A review of recent numerical studies of data centers is presented and compared to available measurements and characterization studies. Results for different air cooling protocols are presented and ranked according to their overall performance. A detailed discussion of the impact of blockages in the plenum, due to wiring and cooling water pipes, is presented and general design guidelines are made pertaining to placement of such blockages. Specific attention is given to the modeling of data centers during dynamic fluctuations in power, airflow, and temperature. This is of particular relevance for the establishment of dynamic self-regulating data centers that may be optimized to operate at the lowest possible energy level while they are meeting specific performance metrics. A case is made for verified reduced order modeling of dynamic data centers. Such an approach may be the most suitable and pragmatic one to achieve real-time holistic models that are capable of predicting and optimizing the overall performance of complex data centers.
Optimization of Data Center Room Layout to Minimize Rack Inlet Air Temperature
Journal of Electronic Packaging, 2006
In a typical raised floor data center with alternating hot and cold aisles, air enters the front ... more In a typical raised floor data center with alternating hot and cold aisles, air enters the front of each rack over the entire height of the rack. Since the heat loads of data processing equipment continue to increase at a rapid rate, it is a challenge to maintain the temperature of all the racks within the stated requirement. A facility manager has discretion in deciding the data center room layout, but a wrong decision will eventually lead to equipment failure. There are many complex decisions to be made early in the design as the data center evolves. Challenges occur such as optimizing the raised floor plenum, floor tile placement, minimizing the data center local hot spots, etc. These adjustments in configuration affect rack inlet air temperatures, which is one of the important keys to effective thermal management. In this paper, a raised floor data center with 12kW racks is considered. There are four rows of racks with alternating hot and cold aisle arrangement. Each row has six...
BioMed2008-38096 APPLICATION OF SPLIT FLOW DESIGN TECHNIQUE TO SIMPLE MICROCHANNEL GEOMETRIES FOR ENHANCED MIXING
The ability to control mixing of reagents in MEMS systems is crucial for many biological and chem... more The ability to control mixing of reagents in MEMS systems is crucial for many biological and chemical analysis applications. However mixing in these microfluidic devices is a challenge because the flows are laminar corresponding to very low Reynolds number. In this paper mixing of such reagents in simple microchannel geometries is investigated computationally. A novel concept of "split flow design" is applied to these simple microchannel configurations. Significant improvement in mixing is seen by employing the split flow design technique.
Publication Guidelines: Final Manuscript Preparation
This paper describes a systematic experimental and numerical study of the thermal characterizatio... more This paper describes a systematic experimental and numerical study of the thermal characterization of a flip-chip package. A cold-plate based test method is used for thermal characterization and internal thermal resistance is used as the basis of all comparisons. Experiment results are presented for three flip-chip packages. Test parameters such as thermocouple wire, attachment, thickness of interface material (grease) between the package lid and the cold plate and power dissipation are presented. Using a detailed numerical model [1], of the package, a parametric study of the experimental method is presented. The parametric study shows the variation in package thermal resistance due to different thermocouple bead sizes, thermocouple attachment parameters, different thermal grease thicknesses and different chip-lid thermal interface material (TIM1) properties. All the numerically predicted values are within the experimental range. NOMENCLATURE [2] u velocity ρ mass density g accelera...
Isolated active cooling system for noise management
Study of transport processes from macroscale to microscale
Honeycomb Body Interdigitated Mixers and Methods for Producing
Honeycomb Body Devices Having Slot-Shaped Intercellular Apertures
Honeycomb Body U-Bend Mixers
Method For Making A Solder Joint
Thermal modeling approach for enhancing TCNCP process for manufacturing fine pitch copper pillar flip chip packages
Additional Conferences (Device Packaging, HiTEC, HiTEN, & CICMT), 2013
Flip chip technology has traditionally been driven by electrical performance and package miniatur... more Flip chip technology has traditionally been driven by electrical performance and package miniaturization, with application processors being primary drivers for devices like smart-phones and tablets. Today solder interconnect pitches, for both low-end and high-end flip chip applications, approximately range from 200μm to 90μm in area array. Advanced silicon nodes create challenges to fine pitch flip chip interconnects and corresponding substrate technology. Fine pitch (<60μm pitch) flip chip (FPFC) packaging is an emerging technology that meets the demand for both smaller form factors and lower cost products. Copper pillar bumps are best suited for fine pitch applications because they allow low standoff height and robust package reliability. Previous feasibility studies show that thermo-compression bonding process with non-conductive paste (NCP) is well suited for manufacturing copper pillar based FPFC packages because the NCP paste encapsulates the bumps and protects the vulnerab...
Power Allocation Towards Hermetic Solder Joint Health of High Powered MEMS Chip for Harsh Environment Applications
ASME 2011 Pacific Rim Technical Conference and Exhibition on Packaging and Integration of Electronic and Photonic Systems, MEMS and NEMS: Volume 1, 2011
ABSTRACT Solders have been utilized extensively in the MEMS packaging industry to create vacuum o... more ABSTRACT Solders have been utilized extensively in the MEMS packaging industry to create vacuum or hermetic seals in a variety of applications. MEMS technology is finding applications in wide range of products like pressure sensors, actuators, flow control devices etc. For many harsh low temperature environment applications, like commercial refrigeration systems, MEMS based pressure sensors and flow actuators are directly mounted on to metal substrates using solders to create hermetic sealing. Solders attaching silicon devices directly to metal substrates may be subjected to very high thermal stresses due to significant difference in thermal expansion coefficients during chip operation or environment temperatures. In this paper, case study of a high powered MEMS chip (referred in the paper as die) operating in a commercial refrigeration system is presented. Accelerated test method for qualifying solder joint for high pressure applications is briefly discussed. Lab experiments showing typical refrigeration cycle thermal load on solder joint are presented. Based on the study, concepts of die power toggling and power allocation towards enhancing hermetic solder joint reliability are discussed. Detailed numerical case studies are presented to quantify the improvement in solder joint reliability due to the proposed concept.
Devices and fluid flow methods for improving mixing
Numerical investigation of underfloor obstructions in open-contained data center with fan curves
Fourteenth Intersociety Conference on Thermal and Thermomechanical Phenomena in Electronic Systems (ITherm), 2014
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Papers by Siddharth Bhopte