scholarly journals An Experimental Study of Coolant Combustion Effects in Transpiration Cooling

1971 ◽  
Author(s):  
J. P. C. Jenczmionka ◽  
R. L. Gorton
Keyword(s):  
Heat Transfer ◽  
Experimental Study ◽  
Surface Temperature ◽  
Hydrogen Combustion ◽  
The Other ◽  
Porous Surface ◽  
Transpiration Cooling ◽  
Temperature Reduction ◽  
Surface Temperatures

Hydrogen, ammonia, and nitrogen coolants were used in a study of combustion effects on transpiration cooling. It was found that hydrogen combustion at low coolant blowing rates resulted in increased porous surface temperatures. However, at higher blowing rates (F > 0.002), hydrogen was more effective in surface temperature reduction than the other coolants. It is demonstrated that assumption of temperature equality of coolant and wall leads to erroneous results in heat transfer determination.

scholarly journals Experimental study of water cooling effect on heat transfer to increase output power of 180 watt peak photovoltaic module

2018 ◽  
Vol 67 ◽  
pp. 01009
Author(s):  
Arrad Ghani Safitra ◽  
Fifi Hesty Sholihah ◽  
Erik Tridianto ◽  
Ikhsan Baihaqi ◽  
Ni Nyoman Ayu Indah T.
Keyword(s):  
Heat Transfer ◽  
Experimental Study ◽  
Surface Temperature ◽  
Output Power ◽  
Cooling Water ◽  
Photovoltaic Module ◽  
Water Cooling ◽  
Water Replacement ◽  
Pv Modules ◽  
Water Height

Photovoltaic (PV) modules require solar radiation to generate electricity. This study aims to determine the effect of water cooling PV modules on heat transfer, output power, and electrical efficiency of PV modules. The experiments carried out in this study were to vary the heights of flooded water (with and without cooling water replacement control) and cooling water flow. Variations in the height of flooded water are 0,5 cm, 1 cm, 2 cm, and 4 cm. While the flow rate variations are 2 L/min, 4 L/min, and 8 L/min. The flooded water replacement control will be active when the PV surface temperature reached 45°C. When the temperature dropped to 35°C, the cooler is disabled to let more photon to reach PV surface. The results showed that the lowest heat transfer occurred in the variation of 4 cm flooded water height without water replacement control, i.e. 28.53 Watt, with an average PV surface temperature of 32.92°C. The highest average electric efficiency occurred in the variation of 0,5 cm flooded water height with water replacement control, i.e. 13.12%. The use of cooling water replacement control is better due to being able to skip more photons reach PV surface with low PV temperature.

The Effect of Thermal Barrier Coating Surface Temperature on the Adhesion Behavior of CMAS Deposits

2020 ◽  
Author(s):  
Robert A. Clark ◽  
Nicholas Plewacki ◽  
Pritheesh Gnanaselvam ◽  
Jeffrey P. Bons ◽  
Vaishak Viswanathan
Keyword(s):  
Heat Transfer ◽  
High Pressure ◽  
Surface Temperature ◽  
Mass Flow ◽  
Experimental Results ◽  
Thermal Barrier ◽  
Back Side ◽  
Surface Temperatures ◽  
The Impact ◽  
Side Flow

Abstract The interaction of thermal barrier coating’s surface temperature with CMAS (calcium magnesium aluminosilicate) like deposits in gas turbine hot flowpath hardware is investigated. Small Hastelloy X coupons were coated in TBC using the air plasma spray (APS) method and then subjected to a thermal gradient via back-side impingement cooling and front-side impingement heating using the High Temperature Deposition Facility (HTDF) at The Ohio State University (OSU). A 1-D heat transfer model was used to estimate TBC surface temperatures and correlate them to intensity values taken from infrared (IR) images of the TBC surface. TBC frontside surface temperatures were varied by changing back-side mass flow (kept at a constant temperature), while maintaining a constant hot-side gas temperature and jet velocity representative of modern commercial turbofan high-pressure turbine (HPT) inlet conditions (approximately 1600K and 200 m/s, or Mach 0.25). In this study, Arizona Road Dust (ARD) was utilized to mimic the behavior of CMAS attack on TBCs. To identify the minimum temperature at which particles adhere, the back-side cooling mass flow was set to the maximum amount allowed by the test setup, and trace amounts of 0–10 μm ARD particles were injected into the hot-side flow to impinge on the TBC surface. The TBC surface temperature was increased through coolant reduction until noticeable deposits formed, as evaluated through an IR camera. Accelerated deposition tests were then performed where approximately 1 gram of ARD was injected into the hot side flow while the TBC surface temperature was held at various points above the minimum observed deposition temperature. Surface deposition on the TBC coupons was evaluated using an infrared camera and a backside thermocouple. Coupon cross sections were also evaluated under a scanning electron microscope for any potential CMAS ingress into the TBC. Experimental results of the impact of surface temperature on CMAS deposition and deposit evolution and morphology are presented. In addition, an Eulerian-Lagrangian solver was used to model the hot-side impinging jet with particles at four TBC surface temperatures and deposition was predicted using the OSU Deposition model. Comparisons to experimental results highlight the need for more sophisticated modeling of deposit development through conjugate heat transfer and mesh morphing of the target surface. These results can be used to improve physics-based deposition models by providing valuable data relative to CMAS deposition characteristics on TBC surfaces, which modern commercial turbofan high pressure turbines use almost exclusively.

An Experimental Study of Heat Transfer During Forced Convection over a Rectangular Body

1980 ◽  
Vol 102 (1) ◽  
pp. 146-151 ◽  
Author(s):  
F. L. Test ◽  
R. C. Lessmann
Keyword(s):  
Heat Transfer ◽  
Experimental Study ◽  
Experimental Investigation ◽  
Aspect Ratio ◽  
Surface Temperature ◽  
Stagnation Point ◽  
Temperature Heat ◽  
Transfer Behavior ◽  
Rectangular Body ◽  
Rectangular Model

An experimental investigation has been performed to determine the constant surface temperature heat transfer behavior on the upper surface of a rectangular model with a chord length of 20.3 cm (8 in.) and an aspect ratio of 6/1. Data were obtained for angles of attack from 0 to 50 deg and freestream velocities of 9.1, 15.2, and 21.3 m/s (30, 50 and 70 ft/s). Separation existed on a portion of the upper surface for angles between 0 and 20 deg with the flow being turbulent after reattachment. Above 30 deg the flow was always laminar with the stagnation point on the upper surface. The heat transfer results in the laminar case were strongly influenced by freestream disturbances.

Surface Effects on Confinement-Driven Pool Boiling Enhancement in Vertical Parallel-Plate Channels

2005 ◽  
Author(s):  
Karl J. L. Geisler ◽  
Avram Bar-Cohen
Keyword(s):  
Heat Transfer ◽  
Experimental Study ◽  
Boiling Heat Transfer ◽  
Parallel Plate ◽  
Nucleate Boiling ◽  
The Other ◽  
Transfer Enhancement ◽  
Channel Spacing ◽  
Boiling Enhancement ◽  
And Behavior

Evidence of confinement-driven boiling heat transfer enhancement in vertical channels is very well documented in the literature and much has been observed about its nature and behavior. However, the majority of the available correlations is empirically-based and they tend to be very restricted in their range of applicability and portability. In order to further elucidate the effect of this type of geometrical confinement on boiling heat transfer, an experimental study has been performed on vertical, rectangular parallel-plate channels immersed in the dielectric liquid FC-72. The enhancement of nucleate boiling performance with decreased channel spacing was found to depend on the type of heater employed but could not be explained by the surface roughness. On the other hand, degradation of the Critical Heat Flux (CHF) limit with decreasing channel spacing was found to be independent of the surface and to be well predicted by a correlation available in the literature.

Experimental Study of Heat Transfer Characteristics of Condensed Flow on the Vertical Wave Plates

2015 ◽  
Vol 776 ◽  
pp. 371-376
Author(s):  
Wahyu H. Piarah ◽  
Zuryati Djafar
Keyword(s):  
Heat Transfer ◽  
Experimental Study ◽  
Heat Transfer Coefficient ◽  
Transfer Coefficient ◽  
The Other ◽  
Vertical Position ◽  
Temperature Profiles ◽  
Heat Transfer Characteristics ◽  
Transfer Characteristics

Studies on the heat transfer characteristics of vertical wave plate subjected to the condensed steam had been done. This research was done to know temperature distribution profiles and heat transfer coefficient on wave plates in vertical position. Temperature profiles were obtained by measuring directly the temperature of test section. On the other hand, determination of heat transfer coefficient was done by using Von Karman’s equation that based on temperature profile.

An Effect of Swept Vane in Hydrogen-Fueled Combustion Turbine

2010 ◽  
Author(s):  
Hironori Honda ◽  
Masaya Suzuki ◽  
Makoto Yamamoto
Keyword(s):  
Surface Temperature ◽  
High Surface ◽  
Three Dimensional ◽  
Aerodynamic Performance ◽  
Hydrogen Combustion ◽  
Hydrogen Gas ◽  
Propulsion System ◽  
The Other ◽  
Other Hand ◽  
Turbine Vane

A lot of environmental problems such as global warning, air pollution and exhaustion of fossil fuels have been discussed frequently. Many researches have been underway in several countries to develop a propulsion system for an advanced aircraft to achieve low environmental loading. On the other hand, with the recent development of an aircraft, the propulsion system is required to have lighter weight, higher power and lower emissions. To satisfy these requirements, we have supposed a new cycle concept for advanced propulsion system, in which the combustion camber is eliminated; hydrogen gas is directly injected from turbine vane surfaces and combusted within turbine vane passages. However, to apply the cycle to practical use, there are problems of extremely high surface temperature and aerodynamic performance decrease by hydrogen combustion. It is well known that three-dimensional design approaches such as sweep, lean and twist decrease the secondary flow loss. However, there is no knowledge how these three-dimensional designs affect on the flow characteristics of the hydrogen-fueled turbine. In the present study, we focus on sweep. To clarify the sweep effect on the surface temperature and performance of the hydrogen-combustion turbine, three-dimensional numerical simulations based on RANS are carried out. We find that the swept vanes with positive sweep give the aerodynamic performance. On the other hand, the swept vanes with negative sweep suppress the vane surface temperature.

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