Prototype utilizing elastocaloric phenomena to demonstrate surface-to-air convection cooling cycle with nitinol

Libes, David

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https://hdl.handle.net/2142/129978 Copy

Description

Title

Prototype utilizing elastocaloric phenomena to demonstrate surface-to-air convection cooling cycle with nitinol

Author(s)

Libes, David

Issue Date

2025-07-23

Director of Research (if dissertation) or Advisor (if thesis)

Miljkovic, Nenad

Department of Study

Mechanical Sci & Engineering

Discipline

Mechanical Engineering

Degree Granting Institution

University of Illinois Urbana-Champaign

Degree Name

M.S.

Degree Level

Thesis

Keyword(s)

• Nitinol
• elastocaloric
• cooling
• heating

Abstract

Heating, ventilation, and air‑conditioning (HVAC) systems are responsible for more than 20 % of global building‐sector energy consumption and rely on high‑GWP refrigerants that leak into the atmosphere [1]. Solid‑state cooling based on the elastocaloric effect in shape‑memory alloys offers a refrigerant‑free alternative with the potential for higher theoretical coefficients of performance. This study investigates Nitinol (Ni‑Ti), a superelastic, shape‑memory alloy whose adiabatic austenite-martensite transformation produces reversible temperature swings when mechanically loaded. An elastocaloric prototype was built to examine the potential for such a future. The prototype cyclically coils a 1 × 2 mm flat Nitinol wire using an electric motor. Preliminary testing and modeling predict a cooling power of ≈10W and an ideal temperature span of ΔT ≈ 2 K under ±4 % surface strain at .25 Hz. Initial experiments confirm the feasibility of achieving the predicted model and show that this design can be refined in the future to achieve better efficiency. Because the current prototype employs rapid‑prototype plastic components for ease of iteration, its thermal mass and structural compliance limit accurate efficiency and fatigue assessments. Ongoing work therefore focuses on replacing key structural parts with aluminum and stainless‑steel inserts to reduce parasitic heat capacity and improve alignment. The ultimate objective is a metal‑dominant architecture capable of exceeding 10⁶ actuation cycles while delivering the predicted cooling power. By demonstrating a scalable path from concept to instrumented hardware, this project advances elastocaloric cooling toward practical, greenhouse‑gas‑free HVAC applications and establishes a platform for which Nitinol prototypes can be constructed that utilize bending rather than tension which has been under explored in literature thus far.

Graduation Semester

2025-08

Type of Resource

Thesis

Handle URL

https://hdl.handle.net/2142/129978

Copyright and License Information

Copyright 2025 David Libes

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