The Experts below are selected from a list of 942 Experts worldwide ranked by ideXlab platform

Abhilash Suryan - One of the best experts on this subject based on the ideXlab platform.

  • Thermo-fluid dynamics of the effects of water spray on air compression process
    12th European Conference on Turbomachinery Fluid Dynamics and Thermodynamics ETC 2017, 2017
    Co-Authors: Abhay Mohan, D.h. Doh, Abhilash Suryan, Heuy Dong Kim
    Abstract:

    Copyright © by the Authors. In a conventional gas turbine setup, a majority of the output power (more than 60%) from the turbine is spent as Compressor Work. In order to increase the effective output power of the system, it is necessary to cut down the input power requirement of the Compressor. In industries techniques such as 'Wet Compression' are employed to achieve this reduction. The process takes advantage of the high enthalpy of vaporization of water droplets to achieve reduction in the overall temperature of the compressed medium. It is established that the thermodynamic Work required for the compression of a fluid increases monotonically with the increase in fluid temperature. In wet compression process, during the compression of the fluid (i.e. air), fine droplets of water are injected into the medium. The droplets absorb heat from the surrounding medium and start evaporating; thereby reducing the temperature of air which in turn decreases the Compressor Work. In addition to this the mass flow rate of the fuel required by the gas turbine system increases in order to maintain its oxidizer-fuel (O/F) ratio, thereby generating extra power output. To study the fundamental thermodynamic process behind wet compression, a cylinder-piston system containing fine droplets of water suspended in air is considered. The axial inward movement of piston enables compression of the fluid mixture. Properties such as pressure, temperature and relative humidity of compressed air are studied in detail for different parameters such as compression rates, droplet diameter and droplet mass. Thermodynamic curves are generated and power savings achieved via wet compression process are calculated. From the results it is seen that smaller sized droplets, slower speeds of compression and higher percentages of overspray lead towards a higher reduction in Compressor Work.

  • Thermo-Fluid Dynamics of the Effects of Water Spray on Air Compression Process
    12th European Conference on Turbomachinery Fluid Dynamics and hermodynamics, 2017
    Co-Authors: Abhay Mohan, Abhilash Suryan
    Abstract:

    In a conventional gas turbine setup, a majority of the output power (more than 60%) from the turbine is spent as Compressor Work. In order to increase the effective output power of the system, it is necessary to cut down the input power requirement of the Compressor. In indus-tries techniques such as ‘Wet Compression’are employed to achieve this reduction.The process takes advantage of the high enthalpy of vaporization of water droplets to achieve reduction in the overall temperature of the compressed medium. It is established that the thermodynamic Work required for the compression of a fluid increases monotonically with the increase in fluid temperature. In wet compression process, during the compression of the fluid (i.e. air), fine droplets of water are injected into the medium. The droplets absorb heat from the surrounding medium and start evaporating; thereby reducing the temperature of air which in turn decreases the Compressor Work. In addition to this the mass flow rate of the fuel required by the gas tur-bine system increases in order to maintain its oxidizer-fuel (O/F) ratio, thereby generating extra power output. To study the fundamental thermodynamic process behind wet compression, a cylinder-piston system containing fine droplets of water suspended in air is considered. The axial inward move-ment of piston enables compression of the fluid mixture. Properties such as pressure, tempera-ture and relative humidity of compressed air are studied in detail for different parameters such as compression rates, droplet diameter and droplet mass. Thermodynamic curves are gener-ated and power savings achieved via wet compression process are calculated. From the results it is seen that smaller sized droplets, slower speeds of compression and higher percentages of overspray lead towards a higher reduction in Compressor Work.

  • Thermo-fluid dynamic analysis of wet compression process
    Journal of Mechanical Science and Technology, 2016
    Co-Authors: Abhay Mohan, Palani Kumar Chidambaram, Abhilash Suryan
    Abstract:

    Wet compression systems increase the useful power output of a gas turbine by reducing the Compressor Work through the reduction of air temperature inside the Compressor. The actual wet compression process differs from the conventional single phase compression process due to the presence of latent heat component being absorbed by the evaporating water droplets. Thus the wet compression process cannot be assumed isentropic. In the current investigation, the gas-liquid two phase has been modeled as air containing dispersed water droplets inside a simple cylinder-piston system. The piston moves in the axial direction inside the cylinder to achieve wet compression. Effects on the thermodynamic properties such as temperature, pressure and relative humidity are investigated in detail for different parameters such as compression speeds and overspray. An analytical model is derived and the requisite thermodynamic curves are generated. The deviations of generated thermodynamic curves from the dry isentropic curves (PV^γ = constant) are analyzed.

  • Theoretical and Computational Studies on Compression Process of Gas with Water Droplets
    Proceedings of the 3rd International Conference of Fluid Flow Heat and Mass Transfer (FFHMT'16), 2016
    Co-Authors: Palani Kumar Chidambaram, Abhay Mohan, Abhilash Suryan
    Abstract:

    Extended Abstract In a gas turbine, the Compressor typically consumes a major portion of the power produced by the turbine. Therefore, a reduction in the Compressor Work significantly improves the gas turbine power output. The Compressor Work increases monotonically with the air temperature. Inlet fogging is a well known technology used to cool the air before it enters the Compressor. Fine mist is sprayed into the air ahead of the Compressor. The mist evaporates completely before the Compressor reducing the air temperature. A lower initial temperature results in a lower compression Work. Another interesting idea is to use the large latent heat of vaporization of water for cooling the air inside Compressor; a technique called wet compression. The evaporating water droplets absorb the heat as the air is being compressed. This heat removal reduces the air temperature progressively during the compression process and thus effectively reduces the Compressor Work. Although the use of water droplets to cool the air entering Compressor had been studied decades ago both theoretically, numerically and experimentally, there is a renewed interest in this research, recently within the past two decades [1, 2]. In the present study, the two phase compression of air water droplet mixture is numerically and analytically studied and the results are compared and contrasted. The Work is focused on understanding the fundamental concepts associated with two phase compression. Hence, a simple piston-cylinder system is used as the simulation domain for the compression of air water droplet mixture. Axi-symmetric numerical computations were performed using a commercial CFD solver by solving URANS equations with water droplets being modelled by Discrete Phase Method. Analytical predictions were made by iteratively solving thermodynamic relations of compression process coupled with heat and mass transfer relations between air and water droplets. During both numerical and analytical computations, thermodynamic properties such as temperature, pressure, enthalpy, entropy and relative humidity inside the cylinder are monitored and investigated. Parametric studies are then performed to identify the effects of initial relative humidity of air, overspray percentage of water droplets, droplet diameter, and compression rate of the piston individually. Initial results from the study indicate that the reduction in Compressor Work is higher for larger overspray percentage of water droplets, droplets of smaller diameter, and slower compression rate. The initial relative humidity of air however is seen to be insignificant in the Compressor Work reduction. While the results from both numerical and analytical predictions agree qualitatively with each other, they differ quantitatively. The major reason for deviation between the computations is attributed to the presence of spatial gradients in the numerical solver.

  • Thermo-fluid dynamic analysis of wet compression process
    Journal of Mechanical Science and Technology, 2016
    Co-Authors: Abhay Mohan, Palani Kumar Chidambaram, Abhilash Suryan, Heuy Dong Kim
    Abstract:

    © 2016, The Korean Society of Mechanical Engineers and Springer-Verlag Berlin Heidelberg.Wet compression systems increase the useful power output of a gas turbine by reducing the Compressor Work through the reduction of air temperature inside the Compressor. The actual wet compression process differs from the conventional single phase compression process due to the presence of latent heat component being absorbed by the evaporating water droplets. Thus the wet compression process cannot be assumed isentropic. In the current investigation, the gas-liquid two phase has been modeled as air containing dispersed water droplets inside a simple cylinder-piston system. The piston moves in the axial direction inside the cylinder to achieve wet compression. Effects on the thermodynamic properties such as temperature, pressure and relative humidity are investigated in detail for different parameters such as compression speeds and overspray. An analytical model is derived and the requisite thermodynamic curves are generated. The deviations of generated thermodynamic curves from the dry isentropic curves (PVγ = constant) are analyzed.

Abhay Mohan - One of the best experts on this subject based on the ideXlab platform.

  • Thermo-fluid dynamics of the effects of water spray on air compression process
    12th European Conference on Turbomachinery Fluid Dynamics and Thermodynamics ETC 2017, 2017
    Co-Authors: Abhay Mohan, D.h. Doh, Abhilash Suryan, Heuy Dong Kim
    Abstract:

    Copyright © by the Authors. In a conventional gas turbine setup, a majority of the output power (more than 60%) from the turbine is spent as Compressor Work. In order to increase the effective output power of the system, it is necessary to cut down the input power requirement of the Compressor. In industries techniques such as 'Wet Compression' are employed to achieve this reduction. The process takes advantage of the high enthalpy of vaporization of water droplets to achieve reduction in the overall temperature of the compressed medium. It is established that the thermodynamic Work required for the compression of a fluid increases monotonically with the increase in fluid temperature. In wet compression process, during the compression of the fluid (i.e. air), fine droplets of water are injected into the medium. The droplets absorb heat from the surrounding medium and start evaporating; thereby reducing the temperature of air which in turn decreases the Compressor Work. In addition to this the mass flow rate of the fuel required by the gas turbine system increases in order to maintain its oxidizer-fuel (O/F) ratio, thereby generating extra power output. To study the fundamental thermodynamic process behind wet compression, a cylinder-piston system containing fine droplets of water suspended in air is considered. The axial inward movement of piston enables compression of the fluid mixture. Properties such as pressure, temperature and relative humidity of compressed air are studied in detail for different parameters such as compression rates, droplet diameter and droplet mass. Thermodynamic curves are generated and power savings achieved via wet compression process are calculated. From the results it is seen that smaller sized droplets, slower speeds of compression and higher percentages of overspray lead towards a higher reduction in Compressor Work.

  • Thermo-Fluid Dynamics of the Effects of Water Spray on Air Compression Process
    12th European Conference on Turbomachinery Fluid Dynamics and hermodynamics, 2017
    Co-Authors: Abhay Mohan, Abhilash Suryan
    Abstract:

    In a conventional gas turbine setup, a majority of the output power (more than 60%) from the turbine is spent as Compressor Work. In order to increase the effective output power of the system, it is necessary to cut down the input power requirement of the Compressor. In indus-tries techniques such as ‘Wet Compression’are employed to achieve this reduction.The process takes advantage of the high enthalpy of vaporization of water droplets to achieve reduction in the overall temperature of the compressed medium. It is established that the thermodynamic Work required for the compression of a fluid increases monotonically with the increase in fluid temperature. In wet compression process, during the compression of the fluid (i.e. air), fine droplets of water are injected into the medium. The droplets absorb heat from the surrounding medium and start evaporating; thereby reducing the temperature of air which in turn decreases the Compressor Work. In addition to this the mass flow rate of the fuel required by the gas tur-bine system increases in order to maintain its oxidizer-fuel (O/F) ratio, thereby generating extra power output. To study the fundamental thermodynamic process behind wet compression, a cylinder-piston system containing fine droplets of water suspended in air is considered. The axial inward move-ment of piston enables compression of the fluid mixture. Properties such as pressure, tempera-ture and relative humidity of compressed air are studied in detail for different parameters such as compression rates, droplet diameter and droplet mass. Thermodynamic curves are gener-ated and power savings achieved via wet compression process are calculated. From the results it is seen that smaller sized droplets, slower speeds of compression and higher percentages of overspray lead towards a higher reduction in Compressor Work.

  • Thermo-fluid dynamic analysis of wet compression process
    Journal of Mechanical Science and Technology, 2016
    Co-Authors: Abhay Mohan, Palani Kumar Chidambaram, Abhilash Suryan
    Abstract:

    Wet compression systems increase the useful power output of a gas turbine by reducing the Compressor Work through the reduction of air temperature inside the Compressor. The actual wet compression process differs from the conventional single phase compression process due to the presence of latent heat component being absorbed by the evaporating water droplets. Thus the wet compression process cannot be assumed isentropic. In the current investigation, the gas-liquid two phase has been modeled as air containing dispersed water droplets inside a simple cylinder-piston system. The piston moves in the axial direction inside the cylinder to achieve wet compression. Effects on the thermodynamic properties such as temperature, pressure and relative humidity are investigated in detail for different parameters such as compression speeds and overspray. An analytical model is derived and the requisite thermodynamic curves are generated. The deviations of generated thermodynamic curves from the dry isentropic curves (PV^γ = constant) are analyzed.

  • Theoretical and Computational Studies on Compression Process of Gas with Water Droplets
    Proceedings of the 3rd International Conference of Fluid Flow Heat and Mass Transfer (FFHMT'16), 2016
    Co-Authors: Palani Kumar Chidambaram, Abhay Mohan, Abhilash Suryan
    Abstract:

    Extended Abstract In a gas turbine, the Compressor typically consumes a major portion of the power produced by the turbine. Therefore, a reduction in the Compressor Work significantly improves the gas turbine power output. The Compressor Work increases monotonically with the air temperature. Inlet fogging is a well known technology used to cool the air before it enters the Compressor. Fine mist is sprayed into the air ahead of the Compressor. The mist evaporates completely before the Compressor reducing the air temperature. A lower initial temperature results in a lower compression Work. Another interesting idea is to use the large latent heat of vaporization of water for cooling the air inside Compressor; a technique called wet compression. The evaporating water droplets absorb the heat as the air is being compressed. This heat removal reduces the air temperature progressively during the compression process and thus effectively reduces the Compressor Work. Although the use of water droplets to cool the air entering Compressor had been studied decades ago both theoretically, numerically and experimentally, there is a renewed interest in this research, recently within the past two decades [1, 2]. In the present study, the two phase compression of air water droplet mixture is numerically and analytically studied and the results are compared and contrasted. The Work is focused on understanding the fundamental concepts associated with two phase compression. Hence, a simple piston-cylinder system is used as the simulation domain for the compression of air water droplet mixture. Axi-symmetric numerical computations were performed using a commercial CFD solver by solving URANS equations with water droplets being modelled by Discrete Phase Method. Analytical predictions were made by iteratively solving thermodynamic relations of compression process coupled with heat and mass transfer relations between air and water droplets. During both numerical and analytical computations, thermodynamic properties such as temperature, pressure, enthalpy, entropy and relative humidity inside the cylinder are monitored and investigated. Parametric studies are then performed to identify the effects of initial relative humidity of air, overspray percentage of water droplets, droplet diameter, and compression rate of the piston individually. Initial results from the study indicate that the reduction in Compressor Work is higher for larger overspray percentage of water droplets, droplets of smaller diameter, and slower compression rate. The initial relative humidity of air however is seen to be insignificant in the Compressor Work reduction. While the results from both numerical and analytical predictions agree qualitatively with each other, they differ quantitatively. The major reason for deviation between the computations is attributed to the presence of spatial gradients in the numerical solver.

  • Thermo-fluid dynamic analysis of wet compression process
    Journal of Mechanical Science and Technology, 2016
    Co-Authors: Abhay Mohan, Palani Kumar Chidambaram, Abhilash Suryan, Heuy Dong Kim
    Abstract:

    © 2016, The Korean Society of Mechanical Engineers and Springer-Verlag Berlin Heidelberg.Wet compression systems increase the useful power output of a gas turbine by reducing the Compressor Work through the reduction of air temperature inside the Compressor. The actual wet compression process differs from the conventional single phase compression process due to the presence of latent heat component being absorbed by the evaporating water droplets. Thus the wet compression process cannot be assumed isentropic. In the current investigation, the gas-liquid two phase has been modeled as air containing dispersed water droplets inside a simple cylinder-piston system. The piston moves in the axial direction inside the cylinder to achieve wet compression. Effects on the thermodynamic properties such as temperature, pressure and relative humidity are investigated in detail for different parameters such as compression speeds and overspray. An analytical model is derived and the requisite thermodynamic curves are generated. The deviations of generated thermodynamic curves from the dry isentropic curves (PVγ = constant) are analyzed.

W.h. Azmi - One of the best experts on this subject based on the ideXlab platform.

  • Composite nanolubricants in automotive air conditioning system: An investigation on its performance
    IOP Conference Series: Materials Science and Engineering, 2019
    Co-Authors: N.n.m. Zawawi, W.h. Azmi, M.z. Sharif, A.i.m. Shaiful
    Abstract:

    AAC system is an important and necessary system in a vehicle in giving thermal comfort to the automotive cars passenger by reducing the surrounding temperature. The experimental investigation on performance of AAC system using composite nanolubricant provides useful data for future development of automotive cars due to its efficiency in improving the system performance. The AAC test bench was developed and utilized from Perodua Kancil. Cooling capacity, Compressor Work and coefficient of performance (COP) of AAC system using pure lubricant and Al2O3-SiO2/PAG composite nanolubricants had been investigated at different refrigerant charges (95 to 155g) and different speeds (900 to 2100 rpm). The result shows that the cooling capacity and COP of composite nanolubricants increased compared to pure lubricant. Meanwhile, the Compressor Work was reduced. Cooling capacity and COP are relatively increased by 59.91% and 7.72% respectively compared to based lubricant. The maximum reduction achievement for Compressor Work is by 9.35% with 155g refrigerant charge and at 2100 rpm. Therefore, Al2O3-SiO2/PAG composite nanolubricants is recommended to be used as the Compressor lubrication to enhance AAC performances system.

  • Comparative Study of Single and Composite Nanolubricants in Automotive Air-Conditioning (AAC) System Performance
    IOP Conference Series: Materials Science and Engineering, 2019
    Co-Authors: A H Hamisa, N.n.m. Zawawi, W.h. Azmi, M.z. Sharif, A.i.m. Shaiful
    Abstract:

    Various studies by leading experts have shown the effectiveness of nanolubricant in improving the performance of the automotive air conditioning (AAC) system. Along with the advancement of technology, composite nanolubricant have been introduced and have been proven to have better properties than normal nanolubricant. The Al2O3-SiO2/PAG composite nanolubricant have better stability, better heat transfer, and improve tribology characteristic compare to its individual single nanoparticles nanolubricant. However, until now no experiments were conducted to test the effectiveness of composite nanolubricant in the AAC system. An experimental study is then taken by testing the Al2O3-SiO2/PAG in AAC system. The results of this experiment have been compared with results of the previous study that uses Al2O3/PAG and SiO2/PAG in AAC system. It is found that the composite nanolubricant have a high enhancement in the COP and does reduce the Compressor Work of the AAC system. The comparison between Al2O3-SiO2/PAG, Al2O3/PAG and SiO2/PAG nanolubricant demonstrates that Al2O3-SiO2/PAG, has better performance in term of Compressor Work reduction and COP enhancement at an average of 28.7 % and 31.64 %, respectively. At last, it was recommended to use the Al2O3-SiO2/PAG nanolubricant for application in AAC system.

  • Performance improvement in mobile air conditioning system using Al2O3/PAG nanolubricant
    Journal of Thermal Analysis and Calorimetry, 2018
    Co-Authors: A.a.m. Redhwan, W.h. Azmi, M.z. Sharif, Rizalman Mamat, Mahendran Samykano, G. Najafi
    Abstract:

    This paper presents the investigation of Al2O3/PAG nanolubricant performance for a compact vehicle mobile air conditioning (MAC) system. The Al2O3/PAG nanolubricant in this study is prepared by using two-step preparation method and stabilized using 4-Step UV–Vis Spectral Absorbency Analysis. An enhancement in the coefficient of performance (COP), reduction in Compressor Work, and enhancement in the cooling capacity of MAC employing Al2O3/PAG nanolubricant are recorded up to 31%, 26% and 32%, respectively, for 0.010% volume concentration. The current MAC performance is compared with MAC employing SiO2/PAG nanolubricant from previous study. The comparison shows that the Al2O3/PAG nanolubricant has better performance in term of cooling capacity, Compressor Work, and COP at an average of 6%, 8%, and 33%, respectively. Therefore, the finding from this study suggests Al2O3/PAG nanolubricant with a volume concentration of 0.010% as an optimum and best performance nanolubricant for MAC systems.

  • Application of response surface methodology in optimization of automotive air-conditioning performance operating with SiO2/PAG nanolubricant
    Journal of Thermal Analysis and Calorimetry, 2018
    Co-Authors: A.a.m. Redhwan, M.z. Sharif, W.h. Azmi, G. Najafi, N.n.m. Zawawi
    Abstract:

    The effect of Compressor speed, initial refrigerant charge and volume concentrations of SiO2/PAG nanolubricant on the performance of automotive air-conditioning (AAC) system are investigated in this study. Response surface method (RSM) was used in designing the experimental Work and is based on face composite design. The developed quadratic models from RSM were helpful to envisage the response parameters namely heat absorbs, Compressor Works, and coefficient of performance (COP) to identify the significant relations between the input factors and the responses. The results depicted that adding SiO2 nanoparticle into PAG lubricant will enhance the COP of AAC. Optimization of independent variables was performed using the desirability approach of the RSM with the goal of maximizing the heat absorb and COP, consequently, minimizing the Compressor Work. The results revealed that the optimal condition with a high desirability of 73.4% for the Compressor speed of 900 rpm, refrigerant charge of 95 g and volume concentration of 0.07%. At this condition, the AAC system operated with 193.99, 23.28 kJ kg−1 and 8.27, respectively, for heat absorb, Compressor Work and COP. DoE based on RSM was capable of optimizing the significant parameters which affect AAC performance.

  • Mechanism for improvement in refrigeration system performance by using nanorefrigerants and nanolubricants – A review
    International Communications in Heat and Mass Transfer, 2018
    Co-Authors: M.z. Sharif, W.h. Azmi, Rizalman Mamat, A.i.m. Shaiful
    Abstract:

    Abstract In order to improve the refrigeration system performance, researchers are introduced nanorefrigerants and nanolubricants in the recent development of HVAC system. However, the explanations of the nanoparticles contribution on the basis physical phenomena which affecting the vapor compression refrigeration system (VCRS) are limited in the literature. Hence, this paper presents a review on mechanism for improvement in VCRS performance by using nanorefrigerants and nanolubricants. The heat transfer augmentation, the refinement of refrigerant-oil mixture characteristic, and the tribology properties enhancement are among the major mechanisms that affect the VCRS performance. The performance parameters of VCRS such as Compressor Work and COP of refrigeration system using nanorefrigerants and nanolubricants have been discussed to relate between the mechanisms with overall system performance. The results showed that the utilization of nanorefrigerants and nanolubricants in the system was increased the heat transfer coefficients from 12 to 101% and the thermal conductivity enhancement for up to 4%. The solubility and miscibility of refrigerant-oil mixture with nanoparticles additives was enhanced for up to 12% although some reported that it was remained unchanged. The nanolubricants were behaved better tribology characteristics with 32% and 13% reduction of friction coefficient and wear rate, respectively. The effect of nanorefrigerants and nanolubricants on heat transfer, refrigerant-oil mixture and tribology had increased the overall performance of VCRS with 11% Compressor Work reduction and 24% of COP enhancement. Therefore, the nanorefrigerants and nanolubricants are expected to become the best candidate towards improving the efficiency of the VCRS.

Heuy Dong Kim - One of the best experts on this subject based on the ideXlab platform.

  • Thermo-fluid dynamics of the effects of water spray on air compression process
    12th European Conference on Turbomachinery Fluid Dynamics and Thermodynamics ETC 2017, 2017
    Co-Authors: Abhay Mohan, D.h. Doh, Abhilash Suryan, Heuy Dong Kim
    Abstract:

    Copyright © by the Authors. In a conventional gas turbine setup, a majority of the output power (more than 60%) from the turbine is spent as Compressor Work. In order to increase the effective output power of the system, it is necessary to cut down the input power requirement of the Compressor. In industries techniques such as 'Wet Compression' are employed to achieve this reduction. The process takes advantage of the high enthalpy of vaporization of water droplets to achieve reduction in the overall temperature of the compressed medium. It is established that the thermodynamic Work required for the compression of a fluid increases monotonically with the increase in fluid temperature. In wet compression process, during the compression of the fluid (i.e. air), fine droplets of water are injected into the medium. The droplets absorb heat from the surrounding medium and start evaporating; thereby reducing the temperature of air which in turn decreases the Compressor Work. In addition to this the mass flow rate of the fuel required by the gas turbine system increases in order to maintain its oxidizer-fuel (O/F) ratio, thereby generating extra power output. To study the fundamental thermodynamic process behind wet compression, a cylinder-piston system containing fine droplets of water suspended in air is considered. The axial inward movement of piston enables compression of the fluid mixture. Properties such as pressure, temperature and relative humidity of compressed air are studied in detail for different parameters such as compression rates, droplet diameter and droplet mass. Thermodynamic curves are generated and power savings achieved via wet compression process are calculated. From the results it is seen that smaller sized droplets, slower speeds of compression and higher percentages of overspray lead towards a higher reduction in Compressor Work.

  • Thermo-fluid dynamic analysis of wet compression process
    Journal of Mechanical Science and Technology, 2016
    Co-Authors: Abhay Mohan, Palani Kumar Chidambaram, Abhilash Suryan, Heuy Dong Kim
    Abstract:

    © 2016, The Korean Society of Mechanical Engineers and Springer-Verlag Berlin Heidelberg.Wet compression systems increase the useful power output of a gas turbine by reducing the Compressor Work through the reduction of air temperature inside the Compressor. The actual wet compression process differs from the conventional single phase compression process due to the presence of latent heat component being absorbed by the evaporating water droplets. Thus the wet compression process cannot be assumed isentropic. In the current investigation, the gas-liquid two phase has been modeled as air containing dispersed water droplets inside a simple cylinder-piston system. The piston moves in the axial direction inside the cylinder to achieve wet compression. Effects on the thermodynamic properties such as temperature, pressure and relative humidity are investigated in detail for different parameters such as compression speeds and overspray. An analytical model is derived and the requisite thermodynamic curves are generated. The deviations of generated thermodynamic curves from the dry isentropic curves (PVγ = constant) are analyzed.

  • Thermo-fluid dynamic analysis on the compression process of liquid-gas two-phase
    Proceedings of the ASME Turbo Expo, 2016
    Co-Authors: Abhay Mohan, Palani Kumar Chidambaram, Abhilash Suryan, Heuy Dong Kim
    Abstract:

    Copyright © 2016 by ASME.In a typical Compressor-turbine cycle, the majority of the output power from the turbine is consumed for the operation of the Compressor. In order to obtain higher output from turbines, certain techniques are employed to reduce Compressor Work. It is known that the Compressor Work increases continually with the increase in temperature of the operating fluid. One of the techniques to achieve reduction of temperature of the fluid is through the inter-cooling between the Compressor stages. But this may lead to the decrease in the overall efficiency of the cycle. Another concept is to utilize the high enthalpy of vaporization of water. One of these techniques is known as wet compression. Here water droplets are introduced into the Compressor and the fluid mixture is compressed. The droplets absorb the heat from the surroundings and evaporate, and thus reduces the temperature of the operating fluid. This in turn decreases the compression Work. Also in order to maintain the O/F ratio of gas turbine, the mass flow rate of the fuel will also increase. All the above mentioned factors thus increase the net power output of the turbine engine. For the current study, a cylinder-piston system containing air involving fine droplets of water is modeled as a simple representation of the wet compression process. The compression process is achieved by the movement of the piston. Thermodynamic properties such as pressure and temperature are investigated in detail for different parameters such as rates of compression, droplet mass and sizes. Analytical equations are derived and validated using the classical D-square law. These equations are used in order to track the change in fluid properties during the compression process and its deviation from dry air compression. The results thus obtained are discussed in terms of the rates of compression, absolute and relative humidities. Corresponding thermodynamic curves are generated which are seen to deviate significantly from the dry isentropic curves. It is observed that smaller diameter droplets, slower speeds of compression and higher amount of overspray percentages lead to lower Compressor Work.

M.z. Sharif - One of the best experts on this subject based on the ideXlab platform.

  • Composite nanolubricants in automotive air conditioning system: An investigation on its performance
    IOP Conference Series: Materials Science and Engineering, 2019
    Co-Authors: N.n.m. Zawawi, W.h. Azmi, M.z. Sharif, A.i.m. Shaiful
    Abstract:

    AAC system is an important and necessary system in a vehicle in giving thermal comfort to the automotive cars passenger by reducing the surrounding temperature. The experimental investigation on performance of AAC system using composite nanolubricant provides useful data for future development of automotive cars due to its efficiency in improving the system performance. The AAC test bench was developed and utilized from Perodua Kancil. Cooling capacity, Compressor Work and coefficient of performance (COP) of AAC system using pure lubricant and Al2O3-SiO2/PAG composite nanolubricants had been investigated at different refrigerant charges (95 to 155g) and different speeds (900 to 2100 rpm). The result shows that the cooling capacity and COP of composite nanolubricants increased compared to pure lubricant. Meanwhile, the Compressor Work was reduced. Cooling capacity and COP are relatively increased by 59.91% and 7.72% respectively compared to based lubricant. The maximum reduction achievement for Compressor Work is by 9.35% with 155g refrigerant charge and at 2100 rpm. Therefore, Al2O3-SiO2/PAG composite nanolubricants is recommended to be used as the Compressor lubrication to enhance AAC performances system.

  • Comparative Study of Single and Composite Nanolubricants in Automotive Air-Conditioning (AAC) System Performance
    IOP Conference Series: Materials Science and Engineering, 2019
    Co-Authors: A H Hamisa, N.n.m. Zawawi, W.h. Azmi, M.z. Sharif, A.i.m. Shaiful
    Abstract:

    Various studies by leading experts have shown the effectiveness of nanolubricant in improving the performance of the automotive air conditioning (AAC) system. Along with the advancement of technology, composite nanolubricant have been introduced and have been proven to have better properties than normal nanolubricant. The Al2O3-SiO2/PAG composite nanolubricant have better stability, better heat transfer, and improve tribology characteristic compare to its individual single nanoparticles nanolubricant. However, until now no experiments were conducted to test the effectiveness of composite nanolubricant in the AAC system. An experimental study is then taken by testing the Al2O3-SiO2/PAG in AAC system. The results of this experiment have been compared with results of the previous study that uses Al2O3/PAG and SiO2/PAG in AAC system. It is found that the composite nanolubricant have a high enhancement in the COP and does reduce the Compressor Work of the AAC system. The comparison between Al2O3-SiO2/PAG, Al2O3/PAG and SiO2/PAG nanolubricant demonstrates that Al2O3-SiO2/PAG, has better performance in term of Compressor Work reduction and COP enhancement at an average of 28.7 % and 31.64 %, respectively. At last, it was recommended to use the Al2O3-SiO2/PAG nanolubricant for application in AAC system.

  • Performance improvement in mobile air conditioning system using Al2O3/PAG nanolubricant
    Journal of Thermal Analysis and Calorimetry, 2018
    Co-Authors: A.a.m. Redhwan, W.h. Azmi, M.z. Sharif, Rizalman Mamat, Mahendran Samykano, G. Najafi
    Abstract:

    This paper presents the investigation of Al2O3/PAG nanolubricant performance for a compact vehicle mobile air conditioning (MAC) system. The Al2O3/PAG nanolubricant in this study is prepared by using two-step preparation method and stabilized using 4-Step UV–Vis Spectral Absorbency Analysis. An enhancement in the coefficient of performance (COP), reduction in Compressor Work, and enhancement in the cooling capacity of MAC employing Al2O3/PAG nanolubricant are recorded up to 31%, 26% and 32%, respectively, for 0.010% volume concentration. The current MAC performance is compared with MAC employing SiO2/PAG nanolubricant from previous study. The comparison shows that the Al2O3/PAG nanolubricant has better performance in term of cooling capacity, Compressor Work, and COP at an average of 6%, 8%, and 33%, respectively. Therefore, the finding from this study suggests Al2O3/PAG nanolubricant with a volume concentration of 0.010% as an optimum and best performance nanolubricant for MAC systems.

  • Application of response surface methodology in optimization of automotive air-conditioning performance operating with SiO2/PAG nanolubricant
    Journal of Thermal Analysis and Calorimetry, 2018
    Co-Authors: A.a.m. Redhwan, M.z. Sharif, W.h. Azmi, G. Najafi, N.n.m. Zawawi
    Abstract:

    The effect of Compressor speed, initial refrigerant charge and volume concentrations of SiO2/PAG nanolubricant on the performance of automotive air-conditioning (AAC) system are investigated in this study. Response surface method (RSM) was used in designing the experimental Work and is based on face composite design. The developed quadratic models from RSM were helpful to envisage the response parameters namely heat absorbs, Compressor Works, and coefficient of performance (COP) to identify the significant relations between the input factors and the responses. The results depicted that adding SiO2 nanoparticle into PAG lubricant will enhance the COP of AAC. Optimization of independent variables was performed using the desirability approach of the RSM with the goal of maximizing the heat absorb and COP, consequently, minimizing the Compressor Work. The results revealed that the optimal condition with a high desirability of 73.4% for the Compressor speed of 900 rpm, refrigerant charge of 95 g and volume concentration of 0.07%. At this condition, the AAC system operated with 193.99, 23.28 kJ kg−1 and 8.27, respectively, for heat absorb, Compressor Work and COP. DoE based on RSM was capable of optimizing the significant parameters which affect AAC performance.

  • Mechanism for improvement in refrigeration system performance by using nanorefrigerants and nanolubricants – A review
    International Communications in Heat and Mass Transfer, 2018
    Co-Authors: M.z. Sharif, W.h. Azmi, Rizalman Mamat, A.i.m. Shaiful
    Abstract:

    Abstract In order to improve the refrigeration system performance, researchers are introduced nanorefrigerants and nanolubricants in the recent development of HVAC system. However, the explanations of the nanoparticles contribution on the basis physical phenomena which affecting the vapor compression refrigeration system (VCRS) are limited in the literature. Hence, this paper presents a review on mechanism for improvement in VCRS performance by using nanorefrigerants and nanolubricants. The heat transfer augmentation, the refinement of refrigerant-oil mixture characteristic, and the tribology properties enhancement are among the major mechanisms that affect the VCRS performance. The performance parameters of VCRS such as Compressor Work and COP of refrigeration system using nanorefrigerants and nanolubricants have been discussed to relate between the mechanisms with overall system performance. The results showed that the utilization of nanorefrigerants and nanolubricants in the system was increased the heat transfer coefficients from 12 to 101% and the thermal conductivity enhancement for up to 4%. The solubility and miscibility of refrigerant-oil mixture with nanoparticles additives was enhanced for up to 12% although some reported that it was remained unchanged. The nanolubricants were behaved better tribology characteristics with 32% and 13% reduction of friction coefficient and wear rate, respectively. The effect of nanorefrigerants and nanolubricants on heat transfer, refrigerant-oil mixture and tribology had increased the overall performance of VCRS with 11% Compressor Work reduction and 24% of COP enhancement. Therefore, the nanorefrigerants and nanolubricants are expected to become the best candidate towards improving the efficiency of the VCRS.