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Synthetic Methodologies of Ester-Based Eco-Friendly, Biodegradable Lubricant Base Stocks for Industrial Applications
Published in Brajendra K. Sharma, Girma Biresaw, Environmentally Friendly and Biobased Lubricants, 2016
Shailesh N. Shah, Sayanti Ghosh, Lalit Kumar, Vivek Rathore, Shivanand M. Pai, Bharat L. Newalkar
Polyolesters are used in a wide variety of applications including engine oils, compressor oils, aviation lubricants, hydraulic fluids, high-temperature chain oils, automotive gear oils, additive carriers, and metalworking fluids [110]. The last decade has witnessed an adoption of polyolester-based lubricants for refrigeration applications as a replacement for mineral oil-based lubricants. This is in accordance with the Kyoto and Montreal protocols to move away from chemicals that have ozone-depleting and global-warming potentials. The polyolesters are compatible with HFC refrigerants which are being used instead of CFC and hydrochlorofluorocarbons. The HFCs have zero ozone-depleting potential. Various viscosity grades of refrigeration lubricants are used in domestic, automotive, and industrial applications and are synthesized using different combinations of polyols and carboxylic acids of varying carbon lengths (Table 12.5). The list of polyols and acids and their combinations required to obtain esters of various viscosity grades is given in Table 12.6. After synthesis, there are standards which have to be met for the certification of polyolester for use as refrigeration lubricant. There are stringent specifications of TAN <0.02 and moisture < 30 ppm that must be met. Even after all the specifications have been met at the synthesis level, detailed testing is necessary before the polyolester finds its way in to the compressor industry. A detailed list of required standard tests of polyolesters for refrigeration application is provided in the following section.
Operational Issues
Published in Reinhard Radermacher, Yunho Hwang, Vapor Compression Heat Pumps, 2005
Reinhard Radermacher, Yunho Hwang
Figure 9.9.5 shows an example for the different HFC refrigerant solubility in the ISO 32 polyolester oil (Corr and Murphy, 1994). As shown in Figure 9.9.5, the solubility of R32 is much lower than that of R125 and R134a due to its low molecular weight. Therefore, R32 resides in the heat exchangers or circulates through the cycle, more so than the other components do if binary mixtures, R32/R125 or R32/R134a, are charged. As the compressor sump temperature decreases, the difference between the refrigerant solubility increases. Even more R32 then migrates to the heat exchangers or circulates in the cycle. However, the impact of the different refrigerant solubility in the oil is not so significant because for large systems, the oil charge is usually smaller than that of the refrigerant charge and the compressor sump temperature is usually high enough to maintain a lower refrigerant solubility. In small systems such as domestic refrigerators, the oil charge can equal or exceed the refrigerant charge and these effects are more important.
Application of Nanofluids in Heat Transfer Enhancement of Refrigeration Systems
Published in K.R.V. Subramanian, Tubati Nageswara Rao, Avinash Balakrishnan, Nanofluids and Their Engineering Applications, 2019
Haque et al. [20] analyzed experimentally the characteristics of a domestic refrigerator using different types and sizes of nanoparticles. Al2O3 and TiO2 nanoparticles were added to the polyolester (POE) oil using different volume fractions of nanoparticles (0.05% and 0.1%). Their experimental results indicated that their system consumed 27.73% and 14.19% less energy when adding 0.1% volume fraction of Al2O3 and TiO2 nanoparticles to the POE oil, respectively. Bi et al. [21] investigated experimentally the performance of a domestic refrigerator using mineral oil with TiO2 nanoparticles mixture as a lubricant instead of polyolester oil in the R134a refrigerator. Their results indicated 26.1% less energy consumption using 0.1% mass fraction of TiO2 nanoparticles compared to the R134a and POE oil system. Jwo et al. [22] conducted an experimental study to analyze the effect of replacing R134a refrigerant and polyolester lubricant oil with hydrocarbon refrigerant and mineral oil containing Al2O3 nanoparticles on the power consumption and coefficient of performance of the refrigeration system. Their results indicated that the use of 60% R134a refrigerant with 0.1% mass fraction of Al2O3 reduced the power consumption by 2.4% and increased the coefficient of performance by 4.4% compared with R134a and POE oil lubricant. Moreover, the authors indicated in their study that replacing R134a refrigerant with hydrocarbon refrigerant and Al2O3 nanoparticles added to the lubricant oil decreased effectively the power consumption and increased the coefficient of performance of the refrigeration system.
Experimental studies on vapour compression refrigeration system using Al2O3/mineral oil nano-lubricant
Published in Australian Journal of Mechanical Engineering, 2022
Dattatraya G. Subhedar, Jinalkumar Z. Patel, Bharat M. Ramani
Harichandran et al. (2019) investigated the effect of h-BN/Polyolester oil (POE) as a lubricant on the performance of VCR with R134a as a refrigerant. They used 0.1% to 0.4% volume fraction of h-BN nanoparticles in POE oil. In that, they observed 60% enhancement in coefficient of performance (COP) using 0.3% volume concentration nanofluid as compared to base oil with increase in anti-friction behaviour. Pico et al. (2019), using POE/Diamond nanolubricant at 0.2% to 0.5% mass concentration in the VCR system with R410A refrigerant, found a maximum 8% increase in COP. They also observed a reduction in compressor discharge temperature by 4°C that causes reduction in compressor power. Similarly, Prasad and Kumar (2018) investigated performance of CuO and Polyalkylene Glycol (PAG) oil at volume concentration 0.01%, to 0.025% of CuO as a lubricant in the VCR system. They reported approximately 25% increment in COP using nanolubricant as compared to the PAG oil.
Vegetable Oil Based Compressor Oil-optimising of Tribological Characteristics
Published in Australian Journal of Mechanical Engineering, 2022
P. Chengareddy, Arumugam Shanmugasundaram
In this study, a unique polyolester from vegetable oil was successfully formulated for reciprocating air compressor applications. The tribological behaviour of the liner-ring tribo combination of reciprocating air compressor under the influence of vegetable oil-based polyolester lubricant was investigated using pin-on-disc type wear and friction monitor. The summary of the findings is as follows: RSM-based D-optimal design with the desirability approach is appropriate to augment the tribological characteristics of polyolester based compressor oils at different loads and speeds.The optimal conditions for attaining the least COF and SWR are as follows: load-50 N; Speed-762 rpm and compressor oil-PE75. Under these optimal test conditions, a minimal COF of 0.0393 and SWR of 1.85E-5 mm3/Nm were recorded.The XPS spectra confirmed the formation of a wear protective layer over the disc surface lubricated with polyolester-based compressor oil.A comparative smoother wear surface of the pin lubricated by PE75 is attributed to the existence of free fatty acids in the vegetable oil structure and an anti-wear additive molecule present in the synthetic compressor oil, which are collectively responsible for minimising the wear to a great extent.
Experimental comparison of R404A and R452A in refrigeration systems
Published in Science and Technology for the Built Environment, 2020
Atİlla G. Devecİoğlu, Vedat Oruç
R452A can also be used in refrigeration systems working with R404A. R452A is a mixture of the refrigerants R32, R125, and R1234yf at mass proportions of 11%, 59%, and 30%, respectively. The flammability and toxicity of R452A, which shows zeotropic properties, have classified it as A1. It is suitable for medium- and high-temperature refrigeration applications (Honeywell 2017). Considering thermodynamic properties, it has been stated that R452A is suitable for refrigeration units in land and sea vehicles (Lillo et al. 2018). Some significant properties of R404A and R452A refrigerants are given in Table 1, which shows that the GWP values of R404A and R452A refrigerants are 3943 and 1945, respectively. Thus, the GWP value of R452A is about 50% lower than that of R404A. ODP values of the studied refrigerants are zero. Polyolester (POE) type oil is preferred in the compressor for both refrigerants.