The Cylindrical Electrostatic Liquid Film Radiator for Heat Rejection in Space

1994 ◽  
Vol 116 (4) ◽  
pp. 986-992 ◽  
Author(s):  
H. Kim ◽  
S. G. Bankoff ◽  
M. J. Miksis
Keyword(s):  
Waste Heat ◽  
Heat Pipes ◽  
Reynolds Numbers ◽  
Viscous Drag ◽  
Unit Surface Area ◽  
Unit Surface ◽  
Micrometeorite Impact ◽  
Present Design ◽  
New Space ◽  
Liquid Flows

A new space radiator concept has been proposed (Kim et al., 1991, 1992a, b, 1993) in which a thin film of hot liquid, flowing along the inside of a closed membrane, rejects waste heat by radiation to the surroundings. In previous versions, the radiator rotates, supplying most of the driving force for the liquid flow. In the present design, the cylinder is stationary, and the liquid flows circumferentially under its initial momentum. Moderately large Reynolds numbers are required to overcome viscous drag, and prevent excessive thickening of the film. The major design consideration involves the application of an internal electrostatic field to pull the liquid away from the site of a membrane puncture due to micrometeorite impact. Calculations are presented that show that leaks can be stopped with a safety factor of two or more, while the surface wave thus produced is washed harmlessly out of the system. Some preliminary heat transfer performance characteristics are presented. The advantages of this concept include the absence of moving parts and the ease of deployment, compared to rotating units, and a factor of at least three for the reduction of the weight per unit surface area compared to heat pipes.

Calcium Carbonate Formation on Cross-Linked Polyethylene (PEX) and Polypropylene Random Copolymer (PP-r)

2005 ◽  
Vol 128 (2) ◽  
pp. 251-254 ◽  
Author(s):  
Patricia Sanft ◽  
Lorraine F. Francis ◽  
Jane H. Davidson
Keyword(s):  
Calcium Carbonate ◽  
Random Copolymer ◽  
Reynolds Numbers ◽  
Unit Surface Area ◽  
Carbonate Concentration ◽  
Carbonate Formation ◽  
Unit Surface ◽  
Before And After ◽  
Polymer Tubes ◽  
Polypropylene Random Copolymer

The accumulation of calcium carbonate (referred to as scale) on the surface of cross-linked polyethylene and polypropylene random copolymer tubes is compared to that on copper. Water with total calcium and carbonate concentration of 3×10−3M and a pH of approximately 9.1, yielding a supersaturation of 7.8, was pumped through the tubes at a velocity of 0.07m∕s for 2.5, 5, and 7.5h. Flow was laminar with Reynolds numbers of <1000. Sections of the tubes were analyzed at the designated time points to determine the extent of scaling. Results include scanning electron microscope images of the tube surfaces before and after exposure to the supersaturated water and chemical analysis to determine the mass of calcium carbonate per unit surface area. Measured scaling rates of the two polymer tubes are similar to that of copper.

ANALYSIS ON THE EFFECT OF NANO PARTICLES IN WASTE HEAT RECOVERY SYSTEM USING HEAT PIPES BY RSM

2019 ◽  
Vol 14 (1) ◽  
Author(s):  
Gunabal S
Keyword(s):  
Response Surface Methodology ◽  
Heat Recovery ◽  
Waste Heat Recovery ◽  
Waste Heat ◽  
Heat Pipes ◽  
Filling Ratio ◽  
Nano Particles ◽  
Waste Heat Recovery System ◽  
Recovery System ◽  
Heat Recovery System

Waste heat recovery systems are used to recover the waste heat in all possible ways. It saves the energy and reduces the man power and materials. Heat pipes have the ability to improve the effectiveness of waste heat recovery system. The present investigation focuses to recover the heat from Heating, Ventilation, and Air Condition system (HVAC) with two different working fluids refrigerant(R410a) and nano refrigerant (R410a+Al2O3). Design of experiment was employed, to fix the number of trials. Fresh air temperature, flow rate of air, filling ratio and volume of nano particles are considered as factors. The effectiveness is considered as response. The results were analyzed using Response Surface Methodology

Waste Heat Recovery for Powering Mobile Devices Using Thermoelectric Generators and Evaporatively-Cooled Heat Sink

2018 ◽  
Author(s):  
Michael Ozeh ◽  
A. G. Agwu Nnanna
Keyword(s):  
Heat Pipe ◽  
Mobile Devices ◽  
Heat Recovery ◽  
Waste Heat Recovery ◽  
Waste Heat ◽  
Heat Pipes ◽  
Loop Heat Pipe ◽  
Thermoelectric Voltage ◽  
Voltage Generation ◽  
Alternate Source

Powering small electronics like mobile devices off-grid has remained a challenge; hence, there exists a need for an alternate source of powering these devices. This paper examines the efficacy of a novel nanoparticle-immobilized polyethylene wick in maintaining sufficient thermal gradient across a thermoelectric generator to power these devices with energy from waste heat. The work examines several other heat exchangers including heat pipes and loop heat pipe setups. The experimental evidence reveals that the nanoparticle-immobilized polyethylene wick is capable of generating sufficient thermal potential resulting in 5V, which is the minimum voltage required to power small mobile devices. In the opinion of the authors, this is the first ever recorded account of utilizing waste heat to generate enough voltage to power a mobile device. Experiment demonstrated that the nanoparticle-immobilized polyethylene wick showed over 40% thermoelectric voltage generation increment over a plain polyethylene wick and a metal wick in a loop heat pipe setup.

scholarly journals Mpemba Effect- the Effect of Time

2021 ◽  
Author(s):  
Jianan Wang
Keyword(s):  
Gravitational Field ◽  
Surface Area ◽  
Time Effect ◽  
Light Quantum ◽  
Unit Surface Area ◽  
Heat Flows ◽  
Unit Surface ◽  
Average Wavelength ◽  
Nature Of Time ◽  
The Relationship

This paper draws the following conclusions on the nature of time by analyzing the relationship between time and speed, the relationship between time and gravitational field, the gravitational redshift of the photon, and the black-body radiation theorem: Time on an object is proportional to the amount of energy flowing out (or in) per unit time (observer’s time) per unit surface area of the object. When an object radiates energy outward: t'=μB(T) =μσT 4=μnhν/st Where t’ is the time on the object, μ is a constant, B(T) is the radiosity，the total energy radiated from the unit surface area of the object in unit time (observer’s time), σ is the Stefan-Boltzmann constant, T is the absolute temperature, n is the number of the photons radiated, ν is the average frequency of the photons radiated, s is the surface area of the object and t is the time on the observer. When the object radiates energy outward, the higher the energy density of the space (for example the stronger the gravitational field of the space), the smaller the radiosity B(T) of the object in the space, the longer the average wavelength of the light quantum emitted by the object, the slower the time on the object, the longer the life of the system. When the object radiates energy outward, the faster the object moves relative to the ether, the higher the energy density of the local space in which the object is located, the smaller the radiosity B(T) of the object, the longer the average wavelength of the light quantum radiated by the object, the slower the time on the object, and the longer the life of the system. When the object radiates energy outward, the higher the temperature of the object, the greater the object's radiosity B(T), the shorter the average wavelength of the light quantum radiated by the object, the faster the time on the object, and the shorter the life of the system. Applying the above conclusions about the nature of time, the author analyzes the Mpemba effect and the inverse Mpemba effect, and reaches the following conclusion: the Mpemba effect is the time effect produced when heat flows from objects into space, and the "inverse" Mpemba effect is the time effect produced when heat flows from space into objects.

Harvesting Waste Heat Energy from Automobile Engine Exhaust Using Teg with Heat Pipes

2018 ◽  
Vol 7 (4.35) ◽  
pp. 85
Author(s):  
Arun Seeralan Balakrishnan ◽  
Farrukh Nagi ◽  
Khairul Salleh ◽  
Prem A/L Gunnasegaran
Keyword(s):  
Finite Element ◽  
Waste Heat ◽  
Heat Removal ◽  
Heat Pipes ◽  
Heat Energy ◽  
Exhaust Pipe ◽  
Cold Side ◽  
Exhaust Heat ◽  
Pipe Line ◽  
Nano Fluids

This research investigates how the heat from car exhaust pipe line can be recovered as power using passive Thermo electric generator (TEG) using heat pipes. In this research the heat pipes are place on the cold side of TEG to remove the rising temperature and hot side of TEG is placed on the circumference of exhaust pipe line of car engine. The heat pipes with and without nano-fluids were placed on cold side of TEGs to investigate heat removal from increasing temperature and too maintain constant temperature on cold side. On the basis of results from 3D finite element simulations and experiments in the setup, the heat flow, voltage, and current were measured. The method presented in this paper gives detailed insight into how TEG modules perform in general, and also enables prediction of potential improvement in module performance by using different nano-fluids as coolants and Preliminary results were obtained. The results of Finite Element Analysis are analogous with the experimental results of TEG with water filled heat pipes with minimal possible errors. Therefore, the performance of nano-fluids in heat pipes are numerically evaluated and proposal are made for the enhancement of Module power outputs in Harnessing exhaust heat energy.

Long-term experimental study of the aquatic plant system for polluted river water

2002 ◽  
Vol 46 (11-12) ◽  
pp. 217-224 ◽  
Author(s):  
K. Sato ◽  
H. Sakui ◽  
Y. Sakai ◽  
S. Tanaka
Keyword(s):  
Surface Area ◽  
Aquatic Plant ◽  
Aquatic Macrophyte ◽  
Unit Surface Area ◽  
Artificial Wetlands ◽  
Polluted River ◽  
Plant System ◽  
Unit Surface ◽  
Experimental Facilities

Water purification using artificial wetlands and aquatic macrophyte is attracting attention as a purification technology that can create rich ecosystems while imposing a minimal load on the environment. Because an aquatic plant system requires a large surface area, design specifications and maintenance methods that can obtain the optimum purification effect per unit surface area must be established. Large experimental facilities have been constructed beside a polluted river flowing into Lake Kasumigaura and have been used for a three-year experiment using several kinds of aquatic plants. This report summarizes the characteristics and the design load of the aquatic plant system based on this study and results from other aquatic plant facilities.

scholarly journals Deceleration of droplets that glide along the free surface of a bath

2016 ◽  
Vol 803 ◽  
pp. 313-331 ◽  
Author(s):  
Jacob Hale ◽  
Caleb Akers
Keyword(s):  
Free Surface ◽  
Wave Motion ◽  
Droplet Diameter ◽  
Reynolds Numbers ◽  
Viscous Drag ◽  
Bath Surface ◽  
Exponential Rate ◽  
Viscous Coupling ◽  
Air Film ◽  
O 10

A droplet obliquely impacting a bath surface of the same fluid can traverse along the interface while slowing at an exponential rate. The droplet rests on a thin film of air, deforms the bath surface creating a dimple and travels along the surface similarly to a wave pulse. Viscous coupling of the droplet and bath surfaces through the air film leads to viscous drag on the bath and perturbs the wave motion of the otherwise free surface. Even though the Reynolds numbers are greater than unity ($\mathit{Re}\,O(10{-}100)$), we show that the droplet’s deceleration is only due to viscous coupling through the air gap. The rate of deceleration is found to increase linearly with droplet diameter.

Fish Community Structure, Biomass, and Production in the Turkey Lakes Watershed, Ontario

1988 ◽  
Vol 45 (S1) ◽  
pp. s115-s120 ◽  
Author(s):  
J. R. M. Kelso
Keyword(s):  
Fish Community ◽  
Carbon Assimilation ◽  
Lake Acidification ◽  
Fish Stock ◽  
Fish Biomass ◽  
Unit Surface Area ◽  
Fish Community Structure ◽  
Fish Flesh ◽  
Unit Surface ◽  
Turkey Lakes Watershed

The Turkey Lakes Watershed contains four lakes, and the headwater lake (Batchawana Lake) consists of two distinct basins, neither of which supports a native, reproducing fish stock. Fish biomass varied by a factor of 3.3 among the other three lakes in the watershed. Fish flesh production varied by a factor of only 1.5 in the system. Salmonid and small cyprinid contribution to biomass and production increased with progression downstream. Both fish biomass and production per unit surface area decreased with increasing lake depth. The fish biomass and production in the watershed was strongly influenced by depth, but alkalinity and phytoplankton carbon assimilation also were related to stock and production. Wishart Lake, immediately below Batchawana Lake, has a fish stock with restricted recruitment, and cyprinids make only a limited contribution to the observed production. Although both these conditions may be symptomatic of lake acidification, it is unclear whether the situation in this watershed results from lake acidification or biogeographic factors.

The catalysis of H 2 —D 2 exchange by oxides

1956 ◽  
Vol 237 (1209) ◽  
pp. 245-254 ◽  
Keyword(s):  
High Activity ◽  
Metal Ion ◽  
Transition Period ◽  
Electronic Configuration ◽  
Hydrogen Chemisorption ◽  
Unit Surface Area ◽  
Simple Correlation ◽  
Common Motif ◽  
Unit Surface ◽  
Tentative Explanation

H 2 —D 2 exchange has been investigated a t the surfaces of 13 oxides of the first transition period, at temperatures between —195 and 20° C and pressures between 1 and 5 cm. There appears to be a simple correlation between the catalytic activity per unit surface area and the electronic configuration of the metal ion. The condition for high activity is that the oxide should possess some but not too many unpaired d -electrons. Thus, high activity occurs just after the beginning of the period (Cr 2 O 3 ) and towards the end (Co 3 O 4 and NiO). If there are no unpaired d -electrons (TiO 2 , V 2 O 5 , Cu 2 O, ZnO, Ga 2 O 3 , GeO 2 ) or very few (V 2 O 3 , CuO) or very many (MnO, Fe 2 O 3 ) the activity is low. A tentative explanation of the results is offered, mainly in terms of the influence of electronic configuration on the velocity of hydrogen chemisorption. The results suggest that hydrogen behaves similarly at metal and at oxide surfaces, giving catalysis by these solids a common motif. There is no simple correlation with oxides between exchange activity and semi-conductivity. Pressure dependences of the exchange velocity have been measured for Cr 2 O 3 , NiO, ZnO and Ga 2 O 3 ; these throw some light on the question of the exchange mechanism.

Sign in / Sign up

Export Citation Format

Share Document