Alfonso Ortega Villanova University Site Director

Associate Vice President Research and Graduate Programs

James R. Birle Professor of Energy Technology

Villanova University

www.villanova.edu/ES2

Villanova University Personnel

Site Director: Dr. Alfonso Ortega

Faculty team:

• Dr. Amy Fleischer, Professor, Thermal Systems

• Dr. Aaron Wemhoff, Asst. Prof, Thermal Systems

• Dr. Jerry Jones, Professor, Thermal Modeling

• Dr. Kamran Fouladi, Research Prof, CFD

Students:

• Luis Silva, Post-Doctoral Research Associate

• Khosrow Ebrahimi, Post-Doctoral Research Associate

• Marcelo Del Valle, PhD Candidate

• Anish Bhalerao, PhD Candidate

• Roozbeh Bahkshi, PhD Candidate

• Daniel Fritch, M.S. Candidate

Villanova University Research

Focus Areas

•Local vs. Grid

•Renewables

•CHP

•DC vs. AC

Power Generation and Distribution

•Smart Scheduling

•Holistic IT and Cooling Processes

Energy Smart IT •VTAS Energy Simulator

•Exergy Based methods for Analysis of Energy Efficient

•Dynamic Close-Coupled Cooling

•Liquid Cooling

Energy Smart Cooling and Energy

Management

•Liquid Cooling to Waste Heat Recovery

•Organic Rankine Cycles

•Absorption Refrigeration

Energy Recovery

DATA CENTER SYSTEM ENERGY MODELING-CHIP TO COOLING TOWER

Villanova University Lead Site

A flow network tool for modeling Data Center energy utilization—Chip to Cooling tower

Physical Layout

Cooling tower

Chiller CRAH Servers & Racks

Room Air

Villanova Thermodynamic Analysis of Systems (VTAS): flow network modeling tool - 1st Law (PUE, WUE) and 2nd Law (exergy destruction) component and system efficiency

calculations - Component design requirement calculations based on data center load - Modeling of transient behavior (e.g., CRAH and/or server failure) - System optimization - Comparison of nontraditional cooling schemes (rear-door heat exchanger, in-row heat

exchanger)

VTAS connects component models via a flow framework

Computational Layout

Cooling tower

Chiller

CRAH

Rack

Tile

Supply plenum

Return plenum

Hot aisle

Cold aisle

Data Center Cooling System Component Models

A large component model library has been created

- Internal component models: - Servers - Data Center airspace (hot aisles, cold

aisles, return plenum, supply plenum, vent tiles)

- Rear-door heat exchangers - In-row coolers

- External component models: - CRAH units - Chillers - Cooling towers

- Other component models: - Fans/pumps - Flow junctions/flow splitters

Component models calculate heat exchange, mass exchange, and exergy destruction

Heat Exchange

Exergy Destruction

Counterflow cooling tower component model with mass exchange

Using Computational Fluid Dynamics as a tool to identify system inefficiencies

Cooling systems cost are directly related to system inefficiencies Inefficiencies are directly related to system irreversibilities Irreversibilities can be identified using EXERGY analysis • We are perfecting the ability to compute EXERGY

DESTRUCTION within a CFD environment • We are EXPORTING that information to the Energy

Simulation tool (VTAS) using a POD technique perfected by our Georgia Tech partners (Joshi et al.)

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Contributions of laminar and turbulent flow components to Exergy destruction

Average:

Fluctuating:

DYNAMIC AND HYBRID COOLING SYSTEMS

Binghamton University, Villanova University, University Texas-Arlington

Dynamic On-Demand Cooling systems

• Synergistic control of cooling with load

• Distributed Close Coupled “Hybrid” cooling systems

• Cooling provided WHERE it is needed WHEN it is needed

Dynamic Local On-Demand Cooling

10 Temperature distribution in a traditional data center Source: http://inres.com/products/tileflow/overview.html

IT characteristics

• Dynamic IT load

• Each rack has different IT loads (Power dissipation)

Legacy air cooling systems

• Cooling does not follow the IT load • Cooling is not localized • Servers are nearly always OVERPROVISIONED

Dynamic data center IT and cooling operation Source: http://www.vigilent.com/news/2012-10-16-vigilent-optimizes-data-center-uptime.php

Hybrid Cooling Systems

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• Hybrid cooling systems such as

in-row, rear-door and over-head

provide localized and dynamic

cooling

• They are a tradeoff between liquid cooling and air cooling

• Air is used to cool the CPUs keeping liquid outside of the racks

• Heat is extracted as close as possible to the server using an air-liquid, cross-flow heat exchanger

• The proximity of the heat exchanger to the heat source increases the opportunities to recover energy

Hybrid air liquid cooling systems; a) In-row cooling system, b) Rear door heat exchanger, c) Over head

cooling system

a) b)

c)

Ongoing Research Active Control of DC Room Airflow Crossflow Air Liquid Heat Exchangers • Complete and compact models to describe

dynamic behavior • Experimental validation

Racks and servers • The transient behavior of servers and racks

has been modeled using numerical simulations and lab experiments

Complex room airflow and associated irreversibilities • CFD and analytical models used to develop

performance metrics and compact models

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Over head cooling system representation

Non-uniform

hot fluid inlet temperature Temperature results Time constant

Modeling of HTX: Impact of heat capacity ratio

Heat capacity rate ratio effect

Results-for smaller E, there is a smaller difference

between the results for the non-uniform and uniform

temperature boundary condition.

Hot fluid

Final value Settling time

Uniform Non-

uniform ∆ Uniform

Non-uniform

∆

E=1 0.3868 0.3495 0.0373 11.52 11.12 0.4

E=0.5 0.2698 0.2492 0.0206 9.38 9.12 0.26

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Additional non-uniform inlet temperature Models

Model 1: Cold fluid non-uniform temperature boundary condition

Non-uniform temperature

boundary conditions are

imposed by making the

temperature vary linearly

across the inlet

All the non-uniform

temperature boundary

conditions have same

mean inlet temperature

Model 2: Hot and Cold fluid non-uniform temperature boundary conditions

The inlet temperature boundary conditions

are both non-uniform; in addition, the hot

fluid inlet temperature is a function of

time as well

Both hot and cold non-uniform

temperature boundary conditions are

specified as a linear function of location

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Dynamic HTX Measurements

Air Heater Section Flow Obstruction Gate Heat Exchanger under Test

Dynamic variation of inlet water temperature Accomplished by controlled mixing of hot and cold fluid streams

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WASTE ENERGY RECOVERY Villanova University, Lead Site

Data Center Waste Heat Recovery Concepts: Mapped by type of cooling

Organic Rankine Cycle

Absorption Refrigeration

HVAC/ Domestic hot

water

District Heating

Boiler feed water heating

Piezoelectrics

Thermoelectrics

Biomass processing

Desalination

Cooling Type Waste heat quality-Max (oC)

#1 (Air-cooled) 50-60

#2 ( Water-cooled) 70-75

#3 (Two-phase cooled) 75-80

# 1 :Yes # 2: Yes # 3: Yes

# 1 :Yes, with booster # 2: Yes # 3: Yes

# 1 :Yes # 2: Yes # 3: Yes

# 1 :Yes, with booster # 2: Yes # 3: Yes

# 1: No # 2: Yes # 3: Yes

# 1: Yes # 2: No # 3: No

# 1: No # 2: No # 3: Yes

# 1: Yes # 2: Yes # 3: Yes

# 1: No # 2: Yes # 3: Yes

Selected by ES2 Industrial mentors for further investigation

Integration of Absorption Refrigeration and ORC to the server/rack cooling cycle

The on-chip two-phase cooling cycle developed by Thome research team at EPFL

The novel configuration to recover the waste heat and convert it to useful cooling- The condenser in on chip cooling cycle is replaced by generator of AR

Simplification of the on-chip cooling cycle and integration into on-chip cooling cycle

The novel configuration to recover the waste heat and convert it to electricity- The condenser in on chip cooling cycle is replaced by evaporator of ORC

Facilities

The Laboratory for Advanced Thermal and Fluid Systems at

Villanova University (Ortega)

www.villanova.edu/latfs

NovaTherm: Villanova’s Thermal Management Laboratory

(Fleischer)

www.villanova.edu/novatherm

Multiscale System Analysis Laboratory (Wemhoff)

www.villanov.edu/MSAL

Thermal and Flow Management of Multiscale Systems

(Jones)

www.villanova.edu/TFM2S/

3/17/2014 ES2 BRIEFING 21

2500 sq. ft. Air Cooling Laboratory 3 ft. Raised Floor

1000 sq. ft. Advanced Technology Laboratory

Labs A & B can be isolated Designed to allow remote launching of experiments and remote measurements Advanced Technology Lab designed for liquid cooling with maximum flexibility

The Villanova-Steel ORCA

Research Center (VSORC)

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Additional University Support

• Villanova NSF ES2 is part of the Villanova Center for the

Advancement of Sustainability in Engineering

• Our students receive University Tuition Fellowships

• Research Experiences for Undergraduate Students

(REU)

• Research Experiences for Teachers (RET)