**2.3 Studies related to TiO2**

Wang et al. [1] performed among the first experimental study using nanorefrigerant which proves that cooling speed and COP of domestic refrigerator significantly enhanced by utilizing TiO2 nanoparticles in R134a based system. Further, Jiang et al. [33] studied the thermal conductivity using new theory and compared with the experimental data using different R22 nanorefrigerant fractions. The investigation proved that particle aggregation theory and the resistance network is a useful method


to calculate the thermal conductivity properties of nanorefrigerant. Li et al. [34] observed that significant improvement at heat transfer coefficient of R11 refrigerant using TiO2 particles. Trisaksri and Wongwises [35] experimentally observed that nucleate pool boiling heat transfer coefficient (HTC) of using R141b refrigerant decreases with increment of TiO2 nanoparticle fractions at high heat fluxes.

*COP comparison of the refrigerant cycle appended with different refrigerants/nanoparticles.*

**Figure 3.**

**Figure 4.**

**105**

*Viscous behavior of mineral oil appended with CuO nanoparticles [29].*

*Effect of Nanoparticles on Performance Characteristics of Refrigeration Cycle*

*DOI: http://dx.doi.org/10.5772/intechopen.89236*

Mahbubul et al. [36] found that pressure drop increases with the addition of TiO2 gradually in base refrigerant. Trisaksri and Wongwises [37] reported that increasing the particle volume fraction decreased the boiling heat transition rate and adding TiO2 particles in base refrigerant R141b deteriorated the heat flow. Bobbo et al. [38] experimentally investigated a study in order to define the effect of TiO2/carbon nanohorns (SWCNH) dispersion on the tribology of compressor polyester oil (SW32). The author reported better performance of TiO2/SW32 blend

**Table 1.**

*Compressor energy consumption using distinct nanoparticle fractions [29].*


**Table 2.**

*Compressor energy consumption of LPG/MO mixture using distinct nanoparticle fractions [46].*

*Effect of Nanoparticles on Performance Characteristics of Refrigeration Cycle DOI: http://dx.doi.org/10.5772/intechopen.89236*

**Figure 3.** *Viscous behavior of mineral oil appended with CuO nanoparticles [29].*

**Figure 4.** *COP comparison of the refrigerant cycle appended with different refrigerants/nanoparticles.*

to calculate the thermal conductivity properties of nanorefrigerant. Li et al. [34] observed that significant improvement at heat transfer coefficient of R11 refrigerant using TiO2 particles. Trisaksri and Wongwises [35] experimentally observed that nucleate pool boiling heat transfer coefficient (HTC) of using R141b refrigerant decreases with increment of TiO2 nanoparticle fractions at high heat fluxes.

Mahbubul et al. [36] found that pressure drop increases with the addition of TiO2 gradually in base refrigerant. Trisaksri and Wongwises [37] reported that increasing the particle volume fraction decreased the boiling heat transition rate and adding TiO2 particles in base refrigerant R141b deteriorated the heat flow. Bobbo et al. [38] experimentally investigated a study in order to define the effect of TiO2/carbon nanohorns (SWCNH) dispersion on the tribology of compressor polyester oil (SW32). The author reported better performance of TiO2/SW32 blend

found 42–82% and 50–101% heat transfer enhancement for 1 and 2% mass fraction respectively. Peng et al. [25] dispersed 0.1 and 0.5 wt% CuO nanoparticles in R113 refrigerant to study heat transfer performance inside a horizontal rough pipe and reported 29.7% HTC using nanoparticles in base refrigerant. Henderson et al. [26] reported lower heat transfer performance with 0.5 and 0.05 vol% of CuO and SiO2 nanoparticles dispersed in R134a and R134a/POE blend during boiling flow conditions in horizontal tube. Further, the author used 0.02, 0.04 and 0.08 vol% of CuO nanoparticles in R134a/POE blend and observed that nanoparticle with 0.04 and 0.08 vol% improved heat transfer performance up to 52 and 76%, respectively. Kedzierski and Gong [27] dispersed 0.5% mass fraction of CuO nanoparticles in polyester oil and observed 275% improvement in heat transfer with base

Later, Bartelt et al. [28] extended the experiment of Kedzierski and Gong [27]

Abdel-Hadi et al. [30] experimentally found that CuO nanoparticles with average size 25 nm and concentration 0.55% is an optimum value which significantly enhanced the evaporative heat transfer coefficient. Kumar et al. [29] observed 7% reduction in compressor energy consumption and 46% enhancement in COP with dispersion of 0.2–1 wt% fraction of CuO nanoparticles in compressor lubricant. Moreover, the author reported reduction in friction and wear in compressor using nanoparticles in base lubricant. Peng et al. [31] used Cu nanoparticle in R113/VG68 (ester oil) mixture. It was observed that using Cu nanoparticles with average size of 20 nm strongly improved the heat transfer performance up to 23.8% as compared to other particles sizes of 50 and 80 nm. Akhavan-Behabadi et al. [32] found 83% increment in heat transfer rate with 1.5% mass fraction of CuO nanoparticles dispersed in R600a/polyester oil condensed inside the smooth horizontal tube

and observed that 2% concentration of CuO nanoparticles gives the highest

Wang et al. [1] performed among the first experimental study using

*Compressor energy consumption using distinct nanoparticle fractions [29].*

nanorefrigerant which proves that cooling speed and COP of domestic refrigerator significantly enhanced by utilizing TiO2 nanoparticles in R134a based system. Further, Jiang et al. [33] studied the thermal conductivity using new theory and compared with the experimental data using different R22 nanorefrigerant fractions. The investigation proved that particle aggregation theory and the resistance network is a useful method

**Nanoparticles concentration 0% 0.2% 0.4% 0.6% 0.8% 1.0%** Energy consumption (kW) 0.113 0.112 0.10 0.107 0.105 0.105 Energy saving (%) — 0.79 3.37 5.55 7.31 7.31

**Nanoparticles concentration 0% 0.2% 0.4% 0.6% 0.8% 1.0%** Energy consumption (kW) 0.1323 0.1278 0.1250 0.1236 0.1224 0.1224 Energy saving (%) — 3.40 5.51 6.57 7.48 7.48

*Compressor energy consumption of LPG/MO mixture using distinct nanoparticle fractions [46].*

improvement up to 101% (**Tables 1** and **2**) [29, 46].

refrigerant R134a.

*Low-temperature Technologies*

(**Figures 3** and **4**) [29, 41, 46].

**2.3 Studies related to TiO2**

**Table 1.**

**Table 2.**

**104**

compared to pure SW32 and SW32/SWCNH mixtures. Bi et al. [39] dispersed TiO2 nanoparticles in R600a refrigerant through compressor lubricant and observed significant increment in freezing capacity about 9.60% by reducing energy consumption up to 5.94% using 0.1 and 0.5 g/L TiO2 nanoparticle. Sabareesh et al. [40] used 0.05–0.015 vol% TiO2 nanoparticles in compressor lubricant and observed that 0.01 vol% is optimum fraction value for better tribological properties. The author reported 17% improvement in COP and 11% reduction compressor energy consumption using nanoparticles with R12. Adelekan et al. [41] observed better COP in refrigerant cycle using TiO2/MO nanolubricant instead of R134a/MO.

The heat transfer rate increases with decreases nanoparticle dimension while the

friction reduction in comparison with base lubricants. TiO2 and CuO are best nanoparticles especially in improvement in tribology characteristics of compressor. It is reported that COP and freezing speed in cooling cycles is increased through application of nanoparticles in base refrigerants. It is found that improvement in VCR system parameters strongly depends on nanoparticle concentration. Thus, optimum value of particle fraction must be defined for better and stable results. Furthermore, the below mentioned suggestions can be considering in future

The nanolubricants have great tribology characteristics in terms of wear rate and

1.As the nanoparticles concentration has great effect on thermophysical and tribology properties of refrigerants/lubricants, the study is needed to find the optimum nanorefrigerants and nanolubricants from the perspective of particle

2.The study on analytical models for the prediction of physical properties is so

3.The study on condensation and evaporation flow of nanorefrigerants is very

4.There are no studies available related to effect of nanoparticles on new blend

5.The studies on the use of nanoparticles with natural refrigerants such as NH3

6.As per literature survey, several studies have been done on positive behavior of nanoparticles on heat transfer enhancement of refrigerants. The studies related

to effect of nanoparticles on basic physical phenomena are somewhere

7.There are no studies available on the flow of nanorefrigerants inside the

Department of Mechanical Engineering, Dr. B.R. Ambedkar National Institute of

© 2019 The Author(s). Licensee IntechOpen. This chapter is distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/ by/3.0), which permits unrestricted use, distribution, and reproduction in any medium,

pressure drop decreases with decreases nanoparticles dimension.

*Effect of Nanoparticles on Performance Characteristics of Refrigeration Cycle*

limited. Future works are needed to viral this study.

size, shapes and flow conditions.

*DOI: http://dx.doi.org/10.5772/intechopen.89236*

limited. It needs to elaborate.

refrigerants such as R1234f.

microchannels and corrugated tubes.

\*Address all correspondence to: gsp.ravinder@gmail.com

and CO2 not performed.

missing.

**Author details**

Ravinder Kumar

**107**

Technology, Jalandhar, India

provided the original work is properly cited.

works:

### **2.4 Studies related to CNTs and other nanoparticles**

Jiang et al. [42] reported 50–104% increment in thermal conductivity with distinct particle fractions and diameters of CNTs dispersed in R113 refrigerant. The author declared 1.0 vol% fraction of CNT as optimum value. Park and Jung [43] performed nucleate boiling heat transfer analysis for CNTs with 1 vol% fraction using R123 and R134a refrigerants. The results found that heat transfer rate was improved (up to 36.6%) at low heat fluxes while it starts decreases at large heat fluxes. Peng et al. [44] reported 61% improvement in heat transfer coefficient with CNTs dispersed in R113/oil blend. Moreover, the author found that higher length and smaller outer diameter increased the heat transfer coefficient. Jiang et al. [42] conducted an experimental study on carbon nanotubes (CNTs) based nanofluids and proposed a modified Yu-Choi model which defined a decent deviation about 5.5% from the experimental result. Henderson et al. [45] used SiO2 particles in polyester oil and reported 55% reduction in flow boiling performance due to the difficulties in nanolubricant dispersion and stability. Whereas, using Al2O3/POE nanolubricant results the great heat transfer improvement.

Kumar and Singh [46] reported 7.48% less energy consumption and 48% higher COP with 1.0 wt% of ZnO nanoparticles dispersed in R290/R600a/MO blend. Peng et al. [47] dispersed diamond nanoparticles in R113/VG68 blend to study nucleate boiling heat transfer coefficient. The author reported 63.4% enhancement in HTC using 0.05–0.5 wt% of nanoparticles fractions. Moreover, the study was compared with CuO/oil blend and found that diamond nanoparticles have higher impact on heat transfer characteristics. Kedzierski [48] reported 98% improvement in boiling heat transfer with 0.5%, 1% and 2% mass fractions of diamond nanoparticles dispersed in R134a. Naphon et al. [49] concentrated on the effect of Ti nanoparticles on the efficiency of copper heat pipe using R11 as base refrigerant. The study reported 0.01% nanoparticle fraction give highest efficiency ratio. Wang et al. [50] used a new category of nano oil which is created by mixing NiFe2O4 nanoparticles into naphthene-based oil B32 as an alternate to polyester VG32 and observed 6% improvement in overall COP.
