Session: Government Agency Student Posters

Paper Number: 173165

Poster for Ultrasonic-Enhanced Dual-Mode Boiling for Next-Generation Cold Plates in Ai Chip Cooling 

This poster presents the development, reported by the NSF PI and team in [1-3], of high-performance cold plates with high heat transfer coefficients (HTC, 60–100 kW/m²·°C) and critical heat flux (CHF, 250–350 W/cm²) for Two-phase Direct-to-Chip (2-Φ D2C) liquid cooling of AI chips in next-generation data centers. Ultrasonic piezoelectric transducer-induced micro-vibrations on micro-structured boiling surfaces enable a second enhancement (ENB-2) beyond enhanced nucleate boiling (ENB-1), which uses R1233zd or similar fluids (e.g., HFE-7000 in experiments). Unlike competing solutions (e.g., Accelsius, ZutaCore), our integrated design methodology combines a micro-structured cold plate, optimized flow loop, and operational protocols, enabling scalable ENB-1 and superior ENB-2 performance for enhanced cold plate and coolant distribution unit (CDU) efficiency.

Ultrasonic micro-vibrations drive ENB-2, inducing controlled flash boiling for 10,000–20,000 hours at low power (<1% TDP) with a high benefit-to-cost ratio. ENB-2 reduces chip temperatures by 15–20°C, requiring minimal material changes (e.g., copper/Monel) and validation on a chip manufacturer’s thermal test vehicle (TTV) with optimized Thermal Interface Material (TIM). This minimizes chip-to-fluid thermal resistance and enhances lateral heat spreading, mitigating hot spots without Direct-to-Silicon cooling.

On-off ultrasonic feather-like vibrations elevate microlayer temperatures of nucleating bubbles, transitioning ENB-1 ebullition cycles [4-7] to ENB-2 via acoustothermal heating [8] and acoustic streaming [9]. This induces transient increases in non-equilibrium liquid-to-vapor mass flux [10] over millisecond-scale advance/recede cycles, driving a sustained vapor-phase pressure rise in the test section, as observed in experiments. Energy balance and Ansys-Fluent modeling confirm that this pressure rise and microlayer temperature increase [1] leverage substrate and fluid thermal inertia to extract significant heat (in joules) from the chip via the cold plate, reducing its temperature by 15–20°C. These low-power vibrations (<1% TDP) shift ENB-1 saturation boiling to ENB-2’s sustained flash boiling in spinodal regions [11].

This approach also enables efficient waste heat recovery into clean electricity, condensing high-pressure R1233zd vapor from data centers into an Organic Rankine Cycle (ORC, using R1233zd) liquid stream via a Heat Recovery Vapor Generator integrated with a Combined Cycle Power Plant (CCPP) gas turbine exhaust.

Experimental and modeling results [1-2] are pictorially highlighted in this poster.

References:

1.      NSF-CBET-2327965-ProjectReport-2025 for new results. Additional findings are disseminated in 4–5 forthcoming journal papers.

2.      Narain, A., H. Bhutka, A. Kanetkar, N. Mohite, “Ultrasonic-Enhanced Nucleate Boiling for Next-Generation Dual-Mode Cold Plates and Flow Systems in AI Chip Cooling,” Submission #173161, July 15, 2025, for Technical Presentation at ASME IMECE 2025.

3.      Narain, A., D. Pandya, J. Damsteegt, and S. Loparo, “A Combined Active (Piezos) and Passive (Microstructuring) Partial Flow-Boiling Approach for Stable High Heat-Flux Cooling with Dielectric Fluids,” Journal of Enhanced Heat Transfer 31(3):45-81 (2024). DOI:10.1615/JEnhHeatTransf.2023050076.

4.      Dhir, Vijay K. "Mechanistic prediction of nucleate boiling heat transfer–achievable or a hopeless task?." (2006): 1-12.

5.      Kim, Jungho. "Review of nucleate pool boiling bubble heat transfer mechanisms." International Journal of Multiphase Flow 35, no. 12 (2009): 1067-1076.

6.      Gerardi, Craig, et al. "Measurement of nucleation site density, bubble departure diameter and frequency in pool boiling of water using high-speed infrared and optical cameras." (2009).

7.      Zhang, Lenan, et al. "A unified relationship between bubble departure frequency and diameter during saturated nucleate pool boiling." International Journal of Heat and Mass Transfer 165 (2021): 120640.

8.      Pillai, Rohit, et al. "Acoustothermal atomization of water nanofilms." Physical Review Letters 121, no. 10 (2018): 104502.

9.      Sadhal, S. S. "Acoustofluidics 13: Analysis of acoustic streaming by perturbation methods." Lab on a Chip 12, no. 13 (2012): 2292-2300. Also see COMSOL 6.1 [2022] for simulating Acoustic Streaming.

10.  Lu, Zhengmao, et al. "A unified relationship for evaporation kinetics at low Mach numbers." Nature Communications 10, no. 1 (2019): 2368.

11.  López, David Reguera. "Nucleation phenomena: The non-equilibrium kinetics of phase change." Contributions to Science 11, no. 2 (2016): 173-180.

Presenting Author: Hardik Bhutka Michigan Technological University

Presenting Author Biography: Hardik Bhutka is currently a graduate student in the Mechanical and Aerospace Engineering Department at Michigan Technological University. My relevant work experience consists of R&D projects at IIT Bombay (2016-2019), and at L&T Technology Services (2022-2024). I have led the development of cold plates for power electronics and the packaging of AC-DC converters. My core expertise spans CAD, FEA simulations, engineering calculations, and hands-on manufacturing. I’ve worked extensively on battery packaging, cooling systems for IGBTs, EV and IC drive-train components, and carbon fiber composites delivering practical and efficient engineering solutions across multiple industries. This diverse experience has equipped me with strong practical skills and the ability to provide effective solutions across a wide range of engineering domains.
Currently, I am pursuing my MS degree under Prof. A. Narain at Michigan Technological University, where I am involved in NSF-funded research on high heat-flux cooling using stable, energy-efficient flow-boiling techniques with micro structured surfaces and ultrasonics (NSF CBET 2327965, PI A. Narain). After finishing my MS, I would evaluate my career options in industry or academia.

Authors:

Hardik Bhutka Michigan Technological University
Amitabh Narain Michigan Technological University
Atharva Kanetkar Michigan Technological University
Nirgun Mohite Michigan Technological University