Heat Dissipation in Confined Space Electronic Devices

Introduction

Most of the industries have adopted industry 4.0 to improve their equipments and processes followed. The equipments are integrated with artificial intelligence and machine learning technologies to convert the system as smarter control systems. Addition of new technologies may increase the surface volume of the device and it will increase the area occupied by the equipments. The inclusion of miniature size heat pipe in the hot core area will significantly reduce the heat flux of the operating devices.

The heat removal from the confined spaces is very difficult; it’s the primary and foremost issue of the devices operating at high heat flux. The heat pipe is a superconductor that is working on the concept of phase change heat transfer; it will dissipate the heat using the latent heat of vaporization and condensation technique. The performance enhancement on the heat pipe is attained by varying its geometrical and operating conditions. Nowadays, micro-heat pipes are often used where conventional sources like air and liquid cooling systems are inadequate to dissipate the heat. In addition, the suspension of the nano-sized high thermal conductive particles in the base fluid will also increase the heat transfer coefficient of the working fluid.


Problems in Cooling of Electronic components

Cooling of electronic devices is essential to remove the waste heat produced due to the continuous working of chips and various components. The high temperature of the devices may lead to permanent damage and reduces the lifetime. Electronic cooling is used to maintain the component temperature within the permissible limit. In addition, these devices required a mechanical pump or a fan to circulate the fluid over the equipment. This is an important two-phase (liquid-vapor) device used in the thermal management of electronics devices. It is a passive device and does not require any external power source. Now, it is widely used in laptops, microprocessors, CPU and GPU of the modern computers.
Source: Moore, etal. 2014

Figure 1 – Heat Dissipation from high heat flux electronic component. (Moore et al., 2014)

The contribution of the heat pipe to the engineering field is remarkable, especially in electronics cooling. Figure 1 represents the removal of heat from electronic components which are operating under high heat flux conditions; heat sink with fins is affixed over PCB board using Thermal Interface Material (TIM).


Super Conducting Heat pipe Heat Exchangers for Confined Spaces

As discussed in previous chapters, the rejection of heat generation of the electronic components is foremost issue. Furthermore, the performance of the existing methods such as a fan or micro fin cooling systems is unsatisfactory even though they occupy a large space. So, the large amount of heat flux that is generated is not removed effectively, which leads to a deterioration in the effective functioning of the electronic devices.
Source: Varma , 2018
Figure 2 – Heat removal from Electronic components using Heat pipes. (SS Varma, 2018)

The effective thermal performance of a heat pipe can be achieved by introducing high thermal conductivity working fluids instead of conventional fluids and varying the geometrical conditions. From the literature survey, it was realized that studies on the heat pipes by varying the parameters like wick structure, working fluid, tilt angle and heat input are not exhaustive and it needs further investigations. The numerical studies on heat pipe are very limited due to the complex nature of the flow to the wick structure, heat transfer with phase change and difficulty in modelling the liquid-vapor interface. Therefore, it was decided to conduct an Elaborative experimental and a basic numerical analysis on the heat pipes to estimate the surface and the vapor temperature distribution, thermal resistance, thermal conductivity, heat transfer co-efficient of the evaporator and condenser sections and the thermal efficiency.


Heat pipe is a well known two-phase heat transfer device; its conductivity is many times higher than any other similar conducting solid materials. The amount of heat transported by a heat pipe depends on its geometry and operating conditions. This section briefly discusses some of the parameters that influence on the thermal characteristics of the heat pipe such as reduction in temperature distribution and temperature difference between the evaporator and condenser sections, thermal resistance, heat transfer rate/heat transfer capability, thermal conductivity, heat transfer coefficient and thermal efficiency.


The difference in temperature between the absorbing and diffusing side of the heat pipe is rapidly reduced when the heat pipe performance is improved. Micro grooved heat pipes are better in heat transfer even though they kept in vertical orientation. Thermal characteristics of heat pipes, improved by dispersing and suspending the tiny sized (called man-sized particles) in the working fluid. The condition of the fluid filled inside the tube may vary with respect to the place where the fluid is located at conditions.


The conventional fluids like water, air, Ethanol are having low thermal conductivity and heat transfer coefficient value. However, these fluids are performing drastically when the velocity of the fluid is raised with external force using the fan for air circulation or peristaltic pump for liquid circulation. The heat pipe ‘s thermal performance improved when the pressure difference between the evaporator and condenser section increases; this pressure difference acting as a driving force which enhances the capillary action and heat transport capacity soon.


In abroad, the solar collector integrated with the compound parabolic collector and heat pipe is used to increase the power conversion efficiency. The present system is proposed to improve the performance using novel nano-coated pulsating heat pipe with the system. The solar collector developer in and around Coimbatore is eager to develop the new solar system to increase the system performance.

Summation

This blog helps the researchers and industries to obtain an idea for incorporating new technologies for improving the system performance by reducing the internal heat generated. This technology is also used in the solar collector and PV panels that operate them effectively under various working conditions. Latest research in electronic cooling focuses on minimizing the surface volume of the component. Introducing the proposed technology helps in drastic reduction of size of electronic components such as laptop, work stations and CPU of integrated industrial equipments, etc.