Tekin, Bilgehan
Yazicioglu, Almila G.
Nanofluids are a class of fluids with nanoparticles suspended in a base fluid. The aim for using nanofluids is often to improve the thermophysical properties of the base fluid so as to enhance the energy transfer efficiency. As the technology develops; the size of devices and systems needs to get smaller to fulfill the engineering requirements and/or to be leading among competitors. The use of nanofluids in heat transfer applications seems to be a viable solution to current heat transfer problems, albeit with certain limitations. As an enhancing factor for the thermal conductivity of the base fluid, nanofluids are considered to be use in cooling system applications. For these applications, the base fluid, the refrigerant, exists as a two-phase liquid-vapor mixture in parts of the refrigeration cycle. To analyze, design and optimize the cycle in such applications, the thermophysical properties of the refrigerant based nanofluids for two-phase flow of refrigerant are needed. There are different models present in the literature derived for the thermophysical properties of nanofluids. However, a majority of the existing models for nanofluid thermophysical properties have been proposed for water- and other liquids-based nanofluids, through theoretical, numerical and experimental research. Therefore, the existing models for determination of the nanofluid thermophysical properties are not applicable for refrigerant based nanofluid applications when the results are compared. Thus, in this work, a new model is derived for the thermal conductivity and viscosity of refrigerant based nanofluids, using existing data from both heat transfer and thermophysical property measurement experiments. The effect of the nanoparticles on heat transfer in two phase flow of the refrigerant is considered by applying the two phase heat transfer correlations in the literature to experimental data. As a result, the thermophysical properties of the known states are determined through known heat transfer performance. Even though the model is developed from the analysis of flow in an evaporator and flow in a single tube with evaporating refrigerant, it is aimed to cover the flows in both evaporator and condenser sections in a vapor compression refrigeration cycle to provide the necessary models for thermophysical properties in heat transfer devices which will allow the design of both cycle and evaporator or condenser in terms of sizing and rating problems by performing heat transfer analysis and/or optimization. The model can also be improved by considering the effects of slip mechanisms that lead to slip velocity between the nanoparticle and base fluid.
ASME Summer Heat Transfer Conference


Effect of Nanoconvection due to Brownian Motion on Thermal Conductivity of Nanofluids
Azizian, M. Reza; AYBAR, HİKMET ŞELLİ; Okutucu Özyurt, Hanife Tuba (2009-08-22)
A nanofluid is a new class of heat transfer fluids that contain a base fluid and nanoparticles. The use of additives is a technique applied to enhance the heat transfer performance of base fluids. The thermal conductivity of the ordinary heat transfer fluids is not adequate to meet today's cooling rate requirements. Nanofluids have been shown to increase the thermal conductivity and convective heat transfer performance of the base liquids. One of the possible mechanisms for anomalous increase in the thermal...
Convective heat transfer enhancement with nanofluids: The effect of temperature-variable thermal conductivity
Özerinç, Sezer; Kakaç, Sadik (2010-07-14)
A nanofluid is defined as the suspension of nanoparticles in a base liquid. Studies in the last decade have shown that significant amount of thermal conductivity and heat transfer enhancement can be obtained by using nanofluids. In the first part of this study, classical forced convection heat transfer correlations developed for pure fluids are used to predict the experimental values of heat transfer enhancement of nanofluids. It is seen that the experimental values of heat transfer enhancement exceed the e...
Thermoluminescence properties of Al doped ZnO nanoparticles
IŞIK, MEHMET; Hasanlı, Nızamı (Elsevier BV, 2018-08-15)
ZnO nanoparticles doped with aluminum (AZO nanoparticles) were investigated using low temperature thermoluminescence (TL) and structural characterization experiments. TL experiments were performed on AZO nanoparticles in the temperature range of 10-300 K. TL curve presented one intensive peak around 123 K and two overlapped peaks to intensive peak around 85 and 150 K for heating rate of 0.1 K/s. Curve fitting and initial rise methods were used to find the activation energies of associated trapping centers. ...
Heat transfer enhancement with nanofluids
Özerinç, Sezer; Güvenç Yazıcıoğlu, Almıla; Department of Mechanical Engineering (2010)
A nanofluid is the suspension of nanoparticles in a base fluid. Nanofluids are promising for heat transfer enhancement due to their high thermal conductivity. Presently, discrepancy exists in nanofluid thermal conductivity data in the literature, and enhancement mechanisms have not been fully understood yet. In the first part of this study, a literature review of nanofluid thermal conductivity is performed. Experimental studies are discussed through the effects of some parameters such as particle volume fra...
Enhanced thermal conductivity of nanofluids: a state-of-the-art review
Özerinç, Sezer; Yazicioglu, Almila Guevenc (2010-02-01)
Adding small particles into a fluid in cooling and heating processes is one of the methods to increase the rate of heat transfer by convection between the fluid and the surface. In the past decade, a new class Of fluids called nanofluids, in which particles of size 1-100 nm with high thermal conductivity are Suspended in a conventional heat transfer base fluid, have been developed. It has been shown that nanofluids containing a small amount of metallic or nonmetallic particles, Such as Al2O3, CuO, Cu, SiO2,...
Citation Formats
B. Tekin and A. G. Yazicioglu, “THERMOPHYSICAL PROPERTIES OF TWO-PHASE REFRIGERANT BASED NANOFLUIDS IN A REFRIGERATION CYCLE,” Washington, DC, 2016, p. 0, Accessed: 00, 2020. [Online]. Available: