This invention presents a practical prototype for waste heat load cooling based on the temperature dependent magnetic response of the ferrofluid termed as thermomagnetic effect. This thermomagnetic effect is the driving force for ferrofluid flow resulting in magnetofluidic cooling (MFC) device. Our MFC device cools down a heat load without using any pump, therefore more compact, noise-free and vibration free. Importantly, MFC device performs self-regulating smart cooling (viz. cooling increases with the increase in heat load and vice versa) by utilizing energy of the waste heat generated from the electronic system or any other heat source. No additional energy other than the waste heat is consumed for MFC.
MFC device utilizes high performance, service temperature tunable, and self-pumping magnetic nanofluids for cooling. MFC is based on the principle of thermomagnetic convection, viz. temperature dependent magnetic response of these nanofluids. The combined effect of magnetic field gradient (∇H) and thermal gradient (∇T) leads to a flow of the cold ferrofluid towards the magnet, pushing hot ferrofluid away from the heat load, resulting in self-regulating cooling. A cooling capacity of 1kW for a heat source temperature at 470°C has been achieved by applying a suitable magnetic field.
Such novel and cost-effective cooling technique with proper heat transfer capability is required for a variety of cooling applications, e.g., electronic systems and buildings. Current cooling approaches for thermal management like micro jet cooling and spray cooling have been widely used in electronic devices. However, these techniques have many drawbacks, e.g. noise, leakage, high maintenance.
Our prototype consists of a torus shaped tube containing ferrofluid, a permanent magnet, a cylindrical heat load, heat sink as the ambient, temperature sensors, and a data logger. A permanent magnet was placed close to the heat load. Thermocouples were placed on the heat load and the heat sink, connected to the temperature data logger, recording the temperature profile vs time. Our lab scale device exhibited magnetofluidic cooling of 145°C for 8W waste heat load at temperature of 230°C.
Our new generation device now enhanced to handle heat load temperatures up to 470°C and power up to 1kW providing cooling of 200°C.
Our approach can be readily extended to cooling of a variety of systems, e.g., electronic devices, HVAC systems, laptop cooling, automobile, battery, building industries, house-hold refrigeration etc. This technology can be embodied in electronic devices and automobiles for the cooling application. Our technique has potential application to improve the energy efficiency of existing building cooling techniques. Such self-cooling and self-regulating magnetofluidic cooling devices have additional applications, especially, where maintenance is difficult such as space craft because there is no moving mechanical part.
By using our technique, lifespan of air conditioning, process equipment, electronic, automobile and building systems can be enhanced. Our cooling technique is noise and vibration free, unlike current cooling technologies. More importantly, some diseases like polio are challenging because of the sensitive nature of vaccines to temperature. Unfortunately, in many remote areas of the developing world, there is an absence of infrastructure and electricity to maintain a temperature controlled system. As a result, numerous life-saving vaccines spoil before their use. This technique can be used to cool these kinds of vaccines and therefore have many customer benefits.