Operating Characteristics of Naphthalene Heat Pipes

Abstract

Heat pipes that operate in the medium temperature range (550-700 K) are very rarely used in industry despite the potential demand of use. There is no consensus about suitable working fluids in this temperature range as research on possible working fluids is limited. One proposed working fluid is naphthalene. In this paper, a number of tests have been undertaken on both an individual naphthalene heat pipe and a naphthalene heat pipe heat exchanger. Unlike room temperature working fluids, medium temperature working fluids are solid at ambient temperature therefore they have unusual transient start up behaviour. Testing has indicated that these heat pipes start to operate when the temperature of the adiabatic section reaches approximately 200 °C. The tested heat pipes were 8 mm in diameter and 278 mm long. The container and mesh material were stainless steel. They were found to have a thermal resistance of approximately 1 °C/W and a maximum rate of heat transfer of 40 W. The orientation was found to have a large effect on the performance of the heat pipes. Compared to the bottom heat mode orientation, when in a horizontal orientation the heat exchanger effectiveness more than halved and when in the top heat mode orientation heat exchanger effectiveness was significantly further reduced.

Synergistic multi-source ambient RF and thermal energy harvester for green IoT applications

“…Many proposed ambient energy harvesters are not universal, ubiquitous, and versatile and are specific to certain locations and use cases only. For example, harvesters from the vibrations of bridges [9][10] and railway trains [11][12][13], vehicle tires [14][15][16][17][18][19], and waste heat of car engines [20][21][22][23][24]. Different combinations of multi-source energy harvesters (MSEHs), such as photovoltaic-thermoelectric-kinetic [25], photovoltaic-triboelectric (raindrops) [26][27][28], photovoltaic-kinetic (water flow) [29], pyroelectric-piezoelectric [30], photovoltaicthermoelectric [31][32][33][34], and electromagnetic-kinetic [35] harvesters, have been reported.…”

Numerical Investigation on the Thermal Performance of a Cascaded Latent Heat Thermal Energy Storage

“…However, phase change materials (PCMs) generally have low thermal conductivity, which limits the heat transfer rate and thermal efficiency of LHTES systems (Mosaffa et al, 2013;Zhao, 2016, 2017). To overcome this disadvantage, scholars have made significant effort to enhance the heat transfer rate, including (1) synthesizing composite phase change materials with high thermal conductivity (Cui et al, 2011;Zhang et al, 2017;Acem et al, 2010); (2) expanding the heat transfer areas, such as adding fins (Ndlovu and Moitsheki, 2019;Hosseini et al, 2015;Al-Abidi et al, 2013); (3) using heat pipes (Shabgard et al, 2010;Singh et al, 2019;Orr, 2019); and (4) using cascaded PCMs. Especially, the cascaded LHTES system can uniform the temperature difference between HTF and PCMs and achieve a high heat transfer rate (Xu et al, 2016).…”

Numerical Analyses on Vapor Pressure Drop in a Centered-Wick Ultra-Thin Heat Pipe

“…In recent years, among many studies on heat pipes (e.g., Mirmanto et al, 2018;Petrucci and Faghri, 2018;Orr et al, 2019;Taft and Irick, 2019), attempts have been made to develop an ultra-thin heat pipe, which has been used especially for the enhancement of cooling of smartphones. Removal of heat is required for smartphones with the increase in performance.…”