This article presents the results of an experimental research on the thermal efficiency (TE) of an evacuated tube solar collector (ETSC) working with a nano-suspension of carbon nanotubes dispersed in distillated water. The efficacy of filling ratio (FR) of the heat pipes; the tilt angle (TA) of the collector, and the dispersion mass fraction of the carbon nanotubes within the distillated water on the TE of the collector was investigated. A model was developed based on the response surface methodology (RSM) to optimize the operating conditions in order to maximize the TE of the collector. The accuracy of the RSM model was verified with some additional experiments. It was found that the RSM model is able to optimize the TE of a collector with the accuracy of 1.6%. Also, it was found that the presence of carbon nanotubes inside the evaporator of the heat pipes can promote the nucleate boiling mechanism which in turn increased the TE of the solar collector. Also, the optimum filling ratio value and the installation angle were identified which were 0.6 and 55°, respectively. This was ascribed to a trade-off trend identified between the exist region inside the thermosyphon heat pipe and the amount of the vapor transported between the condenser and evaporator units, and also a trade-off between the residence time of the carrying fluid and the gravity effect, respectively.

Smart optimization of a thermosyphon heat pipe for an evacuated tube solar collector using response surface methodology (RSM)

Assessment of the thermal performance of a thermosyphon heat pipe using zirconia-acetone nanofluids

The increasing energy consumption of data centers has become a global concern. Over 30% of the total energy use in a data center is consumed by the cooling system and it is necessary to reduce this consumption by efficient cooling techniques. Free cooling is an alternative method, which means utilizing natural cold source when the outdoor temperature is lower than the indoor temperature to achieve energy-saving. Thermosyphon and its integrated system have distinct advantages over other free cooling methods and have great application potential. In this paper, the states of the art are reviewed and overviews are presented for thermosyphon and its integrated system, respectively. The features of existing designs are compared and shortcomings of current studies are concluded. This paper will be helpful for researchers in this field and promote the application of this new free cooling method.

L.G.S. Ribeiro

Papers

Geyser boiling phenomenon in two-phase closed loop-thermosyphons

In-flight testing of loop thermosyphons for aircraft cooling

Passive aircraft cooling systems for variable thermal conditions

Passive cooling concept for onboard heat sources in aircrafts

Thermal performance of thermosyphons in series connected by thermal plugs