Citation: Tang, J.; Luk, P. Wearable Bio-Inspired Pulsating-Flow Cooling for Live Garments Based on a Novel Design of Ferrofluid Micro-Valve. Energies 2022, 15, 8826. https:// doi.org/10.3390/en15238826 Academic Editors: Wenxiao Chu, Lizhong Yang and Qiuwang Wang Received: 22 September 2022 Accepted: 16 November 2022 Published: 23 November 2022 Publisher’s Note: MDPI stays neutral with regard to jurisdictional claims in published maps and institutional affil- iations. Copyright: © 2022 by the authors. Licensee MDPI, Basel, Switzerland. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license (https:// creativecommons.org/licenses/by/ 4.0/). energies Article Wearable Bio-Inspired Pulsating-Flow Cooling for Live Garments Based on a Novel Design of Ferrofluid Micro-Valve † Jiawei Tang and Patrick Luk * Electric Power and Devices Group, Cranfield University, Cranfield MK43 0AL, UK * Correspondence: p.c.k.luk@cranfield.ac.uk † This paper is an extended version of our paper published in 2022 IEEE International Instrumentation and Measurement Technology Conference (I2MTC). IEEE, 2022: 1–6. Abstract: Temperature-related frustrations, such as heat exhaustion, heat stroke, hypothermia, and frost damage, are some of the most prevalent health risks encountered by humans. The aggravation may be lethal for individuals who reside or work in conditions of protracted and high temperature. Temperature-control technologies, such as underfloor heating and air conditioners, have been studied and applied to give individuals with a pleasant and, more crucially, an endurable temperature. However, it may be challenging to install these technologies in an exterior or enclosed space. In addition, they are inflexible for individual requirements, such as mobility and personal-temperature management. A wearable bio-inspired pulsing-flow (discontinuous) cooling system, which can significantly enhance cooling performance, is proposed in this work. The proposed system is implemented with valves to generate pulsating flows. Given that traditional mechanical-valve actuation systems continue to face limits in terms of switching frequency, interface wear loss, and size limitations for wearable-garment applications, a ferrofluid-based shape-controllable micro-valve is proposed to reduce the size and weight of the cooling system. An empirical approach is adopted to avoid the extensive computational simulation of the thermo fluidic dynamics involved, so that efforts can be focused on the design of an innovative scaled prototype built from ferrofluid valves positioned in a specific array of the cooling tubes. This allows the performance of continuous and pulsating cooling-flow systems to be compared on the same flow rate baseline. The results demonstrate that the proposed technology not only delivers superior cooling efficiency, but also has the potential to provide individualized temperature regulation in a “live” garment. Keywords: bio-inspired flow; pulsation cooling; individualized cooling; wearable temperature conditioning; live garment; empirical approach 1. Introduction Temperature-induced deterioration of human bodies has been a major source of public concern for decades. In thermally demanding conditions with excessively hot or cold temperatures, it is critical to keep the body’s temperature within tolerable, if not comfortable, ranges. Air conditioning is one of the most common methods for controlling circumambient temperatures. However, there are situations in which air conditioners are difficult to be implemented and insufficient to fulfil the temperature, mobility and pragmatic requirements of an individual. Therefore, it is highly desirable to have a wearable or portable device capable of providing individualized, adaptable thermal management. Many designs, such as garments, caps, and neck-worn items, have been devel- oped for thermal management [1–6]. Potential consumers of such thermal-management items include, however are not restricted to, the army, the fire department, astronomers, construction-site employees and summer workers in mines [7–10]. People can benefit from simple and cost-effective remedies in the event of heat waves [11]. In the context of this personal-temperature-management application, it is critical to achieve maximum efficiency Energies 2022, 15, 8826. https://doi.org/10.3390/en15238826 https://www.mdpi.com/journal/energies