Pundarika Ganga Naik | Visvesvaraya Technological University (original) (raw)
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Papers by Pundarika Ganga Naik
International Journal of Thermal Engineering, 2015
This work is to study the performance of the thermoacoustic refrigerator with respect to some ope... more This work is to study the performance of the thermoacoustic refrigerator with respect to some operating parameters. The experiments were conducted to evaluate the performance of the thermoacoustic refrigeration system under various operating conditions and different stack geometries. The entire resonator system was constructed from aluminium. The inner surface of the resonator tube was coated with polyurethane material to reduce heat loss from conduction and the resonator tube was filled with Air with the help of regulating systems to the required mean pressure. The factors that influence the performance of the system were identified. The COP of the refrigerator increases with increases of heating load and decreases at higher acoustic power. The temperature difference (ΔT) between hot end and cold end of the stack is higher at 2W heating load for 400Hz operating frequency. The temperature difference across the hot end and cold end of the stack increases with the increase of acoustic power for a mean pressure of 10 bar.
Journal of Applied Fluid Mechanics, 2016
Natural convection heat transfer in a two dimensional unsteady rotating differentially heated enc... more Natural convection heat transfer in a two dimensional unsteady rotating differentially heated enclosure is studied numerically in this paper. The enclosure is filled with air and executes a steady counterclockwise rotation about the centre of the enclosure. A finite volume code on a staggered grid arrangement with TDMA algorithm is developed and employed to solve the governing equations subject to Boussinesq approximation. The numerical investigation is carried out for fixed Prandtl number equal to 0.71, Rayleigh number equal to1.1 10 while Taylors number vary from5.2 10 3.3 10 and Rotational Rayleigh number from 4.9 10 3.1 10 .Results reveal that there are considerable change in heat transfer rates beyond 15 rpm. The effect of rotation on the Nusselt number for a given Rayleigh number is shown in the present work which is not normally indicated and discussed in the available literature
International Journal of Energy Environment and Economics, Nov 1, 2012
Thermal management is the challenge of the day in electronic product development. Oscillating or ... more Thermal management is the challenge of the day in electronic product development. Oscillating or Pulsating Heat Pipe (PHP) is found to be one of the effective cooling devices in such electronic cabinet. In the present work, the experimental studies are carried out on a closed multiple loop PHP with three turns to analyze its characteristics. The steady state experiments are conducted for various heat loads and working fluids. Different fluids viz. Acetone, Methanol, Ethanol, Heptane and Distilled water are used as working fluids during experimentation. The performance parameters of PHP like thermal resistance and heat transfer coefficient are evaluated. The results showed that Heptane and Acetone exhibit better heat transfer characteristics of PHP.
The work reported here deals with the design and optimisation of a thermo acoustic refrigerator (... more The work reported here deals with the design and optimisation of a thermo acoustic refrigerator (TAR) as an attempt to address the future generation environment friendly energy systems. The literature survey gives a complete picture on the history of thermo acoustics and the work carried out in the field of thermo acoustics till today. The motivation of the design of thermo acoustic refrigerator explains the reasons for carrying out the work illustrating its benefits and how the performance of the TAR in future can be made efficient in comparison with the performance of a conventional refrigerator. The general linear theory of thermo acoustics is used as a basis for the design taking simplified assumptions into consideration of the design. Optimization is carried out using MATLAB. The optimisation of different components is carried out to improve the performance and minimise losses in the thermo acoustic refrigerator. For a cooling power of 10 watts, the stack COP was optimized and found to be 2.4948. The acoustic losses in the small diameter resonator tube were minimized by taking the optimized value of the diameter ratio (D2/D1) equal to 0.43.
Applied Mechanics and Materials, 2014
This paper proposes a simplified theoretical model of Pulsating Heat Pipe (PHP) employed in a vap... more This paper proposes a simplified theoretical model of Pulsating Heat Pipe (PHP) employed in a vapour compression refrigeration system. The model developed is mainly based on well known physical equations and partially based on empirical correlation. The present theoretical investigation of PHP is focused to explore its suitability as a heat exchanger in the condenser of vapour compression refrigeration system. A parametric analysis is carried out to design the vapour compression refrigeration system with PHP as the condenser. The performance of the system is evaluated for different PHP diameters, working fluids, evaporator and condenser temperatures and evaporator and condenser lengths. The effect of super heating and sub cooling the refrigerant are also studied. The results showed an increase in performance of the system at higher evaporator and lower condenser temperatures. The best results are obtained with R-12 as the working fluid. Also there is an increase in the COP of the sy...
Sadhana, 2004
Source strength distribution on a jet boundary was obtained from measurements using the principle... more Source strength distribution on a jet boundary was obtained from measurements using the principle of acoustic holography. Measurements were conducted in an open field. Measurement of acoustic pressure on a cylindrical twodimensional contour located close to the vibrating jet boundary was used to obtain the acoustic source strength distribution at the jet boundary. Particular attention was focussed on back projection of the sound field on to a cylindrical surface. A jet emanating from 5 mm convergent nozzle was used for the holography experiments, assuming axisymmetry. Experimental results were compared with results obtained from holography.
International Journal of Sustainable Energy, 2010
This study includes design and experimental analysis of a solar domestic water heating system. Wa... more This study includes design and experimental analysis of a solar domestic water heating system. Water heating systems with glazed and unglazed collectors were constructed and tested at Dhaka, Bangladesh, at a latitude of 23.7 °N. Collector thermal efficiency and capability of raising water temperature were considered as performance evaluation measures. A typical day analysis showed that collector efficiency varied with time
methodology
This paper describes experimental results involving the measurement of acoustic pressure and soun... more This paper describes experimental results involving the measurement of acoustic pressure and sound pressure level (SPL) generated by the jet from an over-expanded convergent-divergent nozzle impinging on a flat plate. The goal of this work is to develop a better understanding of the acoustics of impinging jet flow field, which is of significant practical interest because of its presence in short takeoff and vertical landing (STOVL) vehicles, multi-stage rocket separation, deep space docking, space module attitude control thruster operation, lunar and planetary landing and takeoff , jet engine exhaust impingement, gas turbine blade failure, gun nozzle blast impingement, shock impingement heating, terrestrial rocket launch and other aerospace related and industrial applications. The jet was produced by a convergent-divergent nozzle connected to a settling pressure chamber. Acoustic measurements were made for five different overexpanded jets with chamber-to-ambient pressure ratios,
The heat pipe though has a wide application; the information available towards the development of... more The heat pipe though has a wide application; the information available towards the development of an efficient heat pipe is seldom seen in the open literature. In the present study, investigations are carried out for optimizing the fluid inventory in a typical heat pipe. A "flooded" (with exceedingly large amount of working fluid) heat pipe has slow response and has limited lower range of operation in terms of operating temperature. On the other hand, "starving" (with too little amount of working fluid) heat pipe although exhibits fast response to heat loads, shows severe limit at high temperature conditions. In the present study, an attempt is made to design, fabricate and test a miniature heat pipe with 5 mm diameter and 150 mm length with a thermal capacity of 10 W. Experiments were conducted with and without working fluid for different thermal loads to assess the performance of heat pipe. The working fluids chosen for the study were same as those commonly use...
Applied Mechanics and Materials, 2014
Pulsating heat pipe (PHP) is a passive heat transfer device, which transfers heat from one region... more Pulsating heat pipe (PHP) is a passive heat transfer device, which transfers heat from one region to another with exceptional heat transfer capacity. It utilizes the latent heat of vaporization of the working fluid as well as the sensible heat. As a result, the effective thermal conductivity is higher than that of the conductors. An experimental study on three turn closed loop pulsating heat pipe with three different working fluids viz., Acetone, Methanol, Heptane and distilled water were employed. The PHP is made up of brass material with an inner diameter of 1.95mm, with a total length of 1150 mm for different fill ratios (FR) was employed .The PHP is tested for the thermal resistance and the heat transfer coefficient. The experimental result strongly demonstrates that acetone is a better working fluid among the working fluids considered in terms of higher heat transfer coefficient and lower thermal resistance.
The work reported here deals with the design of a resonator and buffer volume for a Thermo Acoust... more The work reported here deals with the design of a resonator and buffer volume for a Thermo Acoustic Refrigerator (TAR) as an attempt to address the future generation environment friendly energy system. The motivation of the design of thermo acoustic refrigerator explains the reasons for carrying out the work illustrating its benefits and how the performance of the TAR in future can be made efficient in comparison with the performance of a conventional refrigerator. An attempt has been made to design the TAR resonator tube and buffer volume. Further modelling is done by using CATIA and optimization of the design is carried out using MATLAB.
Acoustics Research Letters Online, 2001
The work reported here deals with the design of a Thermo Acoustic Refrigerator (TAR) stack. The m... more The work reported here deals with the design of a Thermo Acoustic Refrigerator (TAR) stack. The motivation of the design of thermo acoustic refrigerator explains the reasons for carrying out the work illustrating its benefits and how the performance of the TAR in future can be made efficient in comparison with the performance of a conventional refrigerator. The design strategy has been described along with the values of the important working gas parameters as well as the non-dimensional parameters. The general linear theory of thermo acoustics is used as a basis for the design taking simplified assumptions into consideration. An attempt has been made to design the TAR by using CATIA. Further modelling and optimization of the design is carried out using MATLAB. The design and optimisation of thermo acoustic refrigerator for a cooling power of 10 watt was designed and it was found that the optimised value of stack COP for 10 watt cooling power was found to be 2.4948 at x sn =0.15 and L sn =0.1.
International Journal of Thermal Engineering, 2015
This work is to study the performance of the thermoacoustic refrigerator with respect to some ope... more This work is to study the performance of the thermoacoustic refrigerator with respect to some operating parameters. The experiments were conducted to evaluate the performance of the thermoacoustic refrigeration system under various operating conditions and different stack geometries. The entire resonator system was constructed from aluminium. The inner surface of the resonator tube was coated with polyurethane material to reduce heat loss from conduction and the resonator tube was filled with Air with the help of regulating systems to the required mean pressure. The factors that influence the performance of the system were identified. The COP of the refrigerator increases with increases of heating load and decreases at higher acoustic power. The temperature difference (ΔT) between hot end and cold end of the stack is higher at 2W heating load for 400Hz operating frequency. The temperature difference across the hot end and cold end of the stack increases with the increase of acoustic power for a mean pressure of 10 bar.
Journal of Applied Fluid Mechanics, 2016
Natural convection heat transfer in a two dimensional unsteady rotating differentially heated enc... more Natural convection heat transfer in a two dimensional unsteady rotating differentially heated enclosure is studied numerically in this paper. The enclosure is filled with air and executes a steady counterclockwise rotation about the centre of the enclosure. A finite volume code on a staggered grid arrangement with TDMA algorithm is developed and employed to solve the governing equations subject to Boussinesq approximation. The numerical investigation is carried out for fixed Prandtl number equal to 0.71, Rayleigh number equal to1.1 10 while Taylors number vary from5.2 10 3.3 10 and Rotational Rayleigh number from 4.9 10 3.1 10 .Results reveal that there are considerable change in heat transfer rates beyond 15 rpm. The effect of rotation on the Nusselt number for a given Rayleigh number is shown in the present work which is not normally indicated and discussed in the available literature
International Journal of Energy Environment and Economics, Nov 1, 2012
Thermal management is the challenge of the day in electronic product development. Oscillating or ... more Thermal management is the challenge of the day in electronic product development. Oscillating or Pulsating Heat Pipe (PHP) is found to be one of the effective cooling devices in such electronic cabinet. In the present work, the experimental studies are carried out on a closed multiple loop PHP with three turns to analyze its characteristics. The steady state experiments are conducted for various heat loads and working fluids. Different fluids viz. Acetone, Methanol, Ethanol, Heptane and Distilled water are used as working fluids during experimentation. The performance parameters of PHP like thermal resistance and heat transfer coefficient are evaluated. The results showed that Heptane and Acetone exhibit better heat transfer characteristics of PHP.
The work reported here deals with the design and optimisation of a thermo acoustic refrigerator (... more The work reported here deals with the design and optimisation of a thermo acoustic refrigerator (TAR) as an attempt to address the future generation environment friendly energy systems. The literature survey gives a complete picture on the history of thermo acoustics and the work carried out in the field of thermo acoustics till today. The motivation of the design of thermo acoustic refrigerator explains the reasons for carrying out the work illustrating its benefits and how the performance of the TAR in future can be made efficient in comparison with the performance of a conventional refrigerator. The general linear theory of thermo acoustics is used as a basis for the design taking simplified assumptions into consideration of the design. Optimization is carried out using MATLAB. The optimisation of different components is carried out to improve the performance and minimise losses in the thermo acoustic refrigerator. For a cooling power of 10 watts, the stack COP was optimized and found to be 2.4948. The acoustic losses in the small diameter resonator tube were minimized by taking the optimized value of the diameter ratio (D2/D1) equal to 0.43.
Applied Mechanics and Materials, 2014
This paper proposes a simplified theoretical model of Pulsating Heat Pipe (PHP) employed in a vap... more This paper proposes a simplified theoretical model of Pulsating Heat Pipe (PHP) employed in a vapour compression refrigeration system. The model developed is mainly based on well known physical equations and partially based on empirical correlation. The present theoretical investigation of PHP is focused to explore its suitability as a heat exchanger in the condenser of vapour compression refrigeration system. A parametric analysis is carried out to design the vapour compression refrigeration system with PHP as the condenser. The performance of the system is evaluated for different PHP diameters, working fluids, evaporator and condenser temperatures and evaporator and condenser lengths. The effect of super heating and sub cooling the refrigerant are also studied. The results showed an increase in performance of the system at higher evaporator and lower condenser temperatures. The best results are obtained with R-12 as the working fluid. Also there is an increase in the COP of the sy...
Sadhana, 2004
Source strength distribution on a jet boundary was obtained from measurements using the principle... more Source strength distribution on a jet boundary was obtained from measurements using the principle of acoustic holography. Measurements were conducted in an open field. Measurement of acoustic pressure on a cylindrical twodimensional contour located close to the vibrating jet boundary was used to obtain the acoustic source strength distribution at the jet boundary. Particular attention was focussed on back projection of the sound field on to a cylindrical surface. A jet emanating from 5 mm convergent nozzle was used for the holography experiments, assuming axisymmetry. Experimental results were compared with results obtained from holography.
International Journal of Sustainable Energy, 2010
This study includes design and experimental analysis of a solar domestic water heating system. Wa... more This study includes design and experimental analysis of a solar domestic water heating system. Water heating systems with glazed and unglazed collectors were constructed and tested at Dhaka, Bangladesh, at a latitude of 23.7 °N. Collector thermal efficiency and capability of raising water temperature were considered as performance evaluation measures. A typical day analysis showed that collector efficiency varied with time
methodology
This paper describes experimental results involving the measurement of acoustic pressure and soun... more This paper describes experimental results involving the measurement of acoustic pressure and sound pressure level (SPL) generated by the jet from an over-expanded convergent-divergent nozzle impinging on a flat plate. The goal of this work is to develop a better understanding of the acoustics of impinging jet flow field, which is of significant practical interest because of its presence in short takeoff and vertical landing (STOVL) vehicles, multi-stage rocket separation, deep space docking, space module attitude control thruster operation, lunar and planetary landing and takeoff , jet engine exhaust impingement, gas turbine blade failure, gun nozzle blast impingement, shock impingement heating, terrestrial rocket launch and other aerospace related and industrial applications. The jet was produced by a convergent-divergent nozzle connected to a settling pressure chamber. Acoustic measurements were made for five different overexpanded jets with chamber-to-ambient pressure ratios,
The heat pipe though has a wide application; the information available towards the development of... more The heat pipe though has a wide application; the information available towards the development of an efficient heat pipe is seldom seen in the open literature. In the present study, investigations are carried out for optimizing the fluid inventory in a typical heat pipe. A "flooded" (with exceedingly large amount of working fluid) heat pipe has slow response and has limited lower range of operation in terms of operating temperature. On the other hand, "starving" (with too little amount of working fluid) heat pipe although exhibits fast response to heat loads, shows severe limit at high temperature conditions. In the present study, an attempt is made to design, fabricate and test a miniature heat pipe with 5 mm diameter and 150 mm length with a thermal capacity of 10 W. Experiments were conducted with and without working fluid for different thermal loads to assess the performance of heat pipe. The working fluids chosen for the study were same as those commonly use...
Applied Mechanics and Materials, 2014
Pulsating heat pipe (PHP) is a passive heat transfer device, which transfers heat from one region... more Pulsating heat pipe (PHP) is a passive heat transfer device, which transfers heat from one region to another with exceptional heat transfer capacity. It utilizes the latent heat of vaporization of the working fluid as well as the sensible heat. As a result, the effective thermal conductivity is higher than that of the conductors. An experimental study on three turn closed loop pulsating heat pipe with three different working fluids viz., Acetone, Methanol, Heptane and distilled water were employed. The PHP is made up of brass material with an inner diameter of 1.95mm, with a total length of 1150 mm for different fill ratios (FR) was employed .The PHP is tested for the thermal resistance and the heat transfer coefficient. The experimental result strongly demonstrates that acetone is a better working fluid among the working fluids considered in terms of higher heat transfer coefficient and lower thermal resistance.
The work reported here deals with the design of a resonator and buffer volume for a Thermo Acoust... more The work reported here deals with the design of a resonator and buffer volume for a Thermo Acoustic Refrigerator (TAR) as an attempt to address the future generation environment friendly energy system. The motivation of the design of thermo acoustic refrigerator explains the reasons for carrying out the work illustrating its benefits and how the performance of the TAR in future can be made efficient in comparison with the performance of a conventional refrigerator. An attempt has been made to design the TAR resonator tube and buffer volume. Further modelling is done by using CATIA and optimization of the design is carried out using MATLAB.
Acoustics Research Letters Online, 2001
The work reported here deals with the design of a Thermo Acoustic Refrigerator (TAR) stack. The m... more The work reported here deals with the design of a Thermo Acoustic Refrigerator (TAR) stack. The motivation of the design of thermo acoustic refrigerator explains the reasons for carrying out the work illustrating its benefits and how the performance of the TAR in future can be made efficient in comparison with the performance of a conventional refrigerator. The design strategy has been described along with the values of the important working gas parameters as well as the non-dimensional parameters. The general linear theory of thermo acoustics is used as a basis for the design taking simplified assumptions into consideration. An attempt has been made to design the TAR by using CATIA. Further modelling and optimization of the design is carried out using MATLAB. The design and optimisation of thermo acoustic refrigerator for a cooling power of 10 watt was designed and it was found that the optimised value of stack COP for 10 watt cooling power was found to be 2.4948 at x sn =0.15 and L sn =0.1.
