scholarly journals Numeric modeling of a micro-scale differential thermal calorimeter for the purpose of cryopreservation

2017 ◽  
Author(s):  
◽  
Han Han
Keyword(s):  
Heat Flux ◽  
Temperature Distribution ◽  
Cooling Rate ◽  
Water Droplet ◽  
Biological Material ◽  
Computational Time ◽  
Freezing Process ◽  
Water Droplets ◽  
Micro Scale ◽  
Numeric Model

Cryopreservation requires biological material to be stored at temperatures well below the freezing point of water. During the process of cryopreservation, the cooling rate should be carefully chosen to avoid cell damage due to the unbalanced pressure and the solution effect. Cellular thermal analysis that determines the thermodynamics properties of a micro-scale biological material is necessary for a successful cryopreservation procedure. A micro-scale differential thermal analyzer (uDTA) was previously developed to obtain accurate thermal properties measurements of freezing cells. However, the thermal signal needs to be properly interpreted in terms of how much ice is created. Also, the future cooling profile needed to experimentally control the cooling rate needs to be developed. So a 3D numeric model was built in STAR CCM+ to study the temperature change of the water droplets while being frozen by a thermoelectric module. The heat flux profile for the boundary condition was scaled to accommodate the heat spread effect. The numeric model solutions successfully matched the temperature distribution results from the experiments. By using additional heat flux to accommodate the heat spread effect, the STAR CCM+ model generated relatively accurate results on a smaller geometry within a very short computational time. This is a big improvement compared with other high fidelity computational simulation models used to solve similar problems. After the 3D model was calibrated, the same STAR CCM+ model was used to predict the temperature distribution of different sizes of water droplets during the freezing process. This model allowed us to better understand the temperature distribution of a water droplet when the water droplet was being cooled until frozen. The modeling technique developed in this research will help establish the required cooling rates needed to control ice formation and establish thermodynamic properties of cell freezing solutions.

Application of Differential Transform Method for Estimating Thermal Cycle Developed in GTA Welding of High Carbon Steel Joints

2015 ◽  
Vol 14 ◽  
pp. 37-48
Author(s):  
Jaideep Dutta ◽  
S. Narendranath ◽  
Aleksandr Zhilin
Keyword(s):  
Heat Flux ◽  
Temperature Distribution ◽  
Carbon Steel ◽  
Cooling Rate ◽  
High Carbon Steel ◽  
Differential Transform Method ◽  
Temperature Cycle ◽  
High Carbon ◽  
Transform Method ◽  
Differential Transform

This article reveals a detailed study of temperature cycle formed during Gas Tungsten Arc welding of high carbon steel (AISI 1090) butt joints. Experimental work has been carried out to estimate the temperature distribution along fusion boundary to longitudinal direction of the weldment by mounting thermocouples on the plate along with Data Acquisition System. Heat flux distribution due to moving point heat source has been demonstrated by implementing Gaussian surface heat flux and Angular Torch model. Cooling rate has predicted by application of Adams cooling rate equation. Conduction-convection phenomena plays dominant role for evaluating heat loss from the weld joint and Differential Transform Method (DTM) has been applied to judge non-dimensional temperature distribution. Analytical studies has shown well agreement with experimental temperature distribution.

The Effect of Cooling Rate on the Formation of Dendritic Ice in a Pipe With No Main Flow

1977 ◽  
Vol 99 (3) ◽  
pp. 419-424 ◽  
Author(s):  
R. R. Gilpin
Keyword(s):  
Temperature Distribution ◽  
Cooling Rate ◽  
Dendritic Growth ◽  
Pipe Wall ◽  
Ice Nucleation ◽  
Thermal Boundary Condition ◽  
Main Flow ◽  
Freezing Process ◽  
Water Pipe ◽  
Flow Through

Dendritic ice forms in a pipe when there is no main flow through the pipe during the freezing process. This ice form occurs because the quiescent water supercools considerably below 0°C before ice nucleation occurs. It has been shown that growth of dendritic ice can cause blockage of a water pipe [1] much sooner than would have been predicted if the ice grew as a solid annulus. The extent of the dendritic growth is largely determined by the temperature distribution that exists in the pipe at the time of ice nucleation. In this paper the factors effecting the temperature distribution and thus the extent of dendritic ice growth are examined to determine the conditions under which blockage by dendritic ice is likely to occur. The factors that are important are the cooling rate the pipe is exposed to, the ice nucleation temperature, and the type of thermal boundary condition the pipe wall provides.

scholarly journals Freezing of water droplets colliding with kaolinite particles

2009 ◽  
Vol 9 (13) ◽  
pp. 4295-4300 ◽  
Author(s):  
E. A. Svensson ◽  
C. Delval ◽  
P. von Hessberg ◽  
M. S. Johnson ◽  
J. B. C. Pettersson
Keyword(s):  
Water Vapor ◽  
Relative Humidity ◽  
Water Droplet ◽  
Supercooled Water ◽  
Dust Particles ◽  
Freezing Process ◽  
Water Droplets ◽  
Electrodynamic Balance ◽  
Dry Conditions

Abstract. Contact freezing of single supercooled water droplets colliding with kaolinite dust particles has been investigated. The experiments were performed with droplets levitated in an electrodynamic balance at temperatures from 240 to 268 K. Under relatively dry conditions (when no water vapor was added) freezing was observed to occur below 249 K, while a freezing threshold of 267 K was observed when water vapor was added to the air in the chamber. The effect of relative humidity is attributed to an influence on the contact freezing process for the kaolinite-water droplet system, and it is not related to the lifetime of the droplets in the electrodynamic balance. Freezing probabilities per collision were derived assuming that collisions at the lowest temperature employed had a probability of unity. Mechanisms for contact freezing are briefly discussed.

IMPROVED LUMPED-DIFFERENTIAL ANALYSIS OF THE FREEZING PROCESS IN A SUPERCOOLED WATER DROPLET

2020 ◽  
Author(s):  
Emerson Barbosa dos Anjos ◽  
Carolina Palma Naveira Cotta ◽  
Renato Machado Cotta ◽  
Igor Soares Carvalho ◽  
Manish Tiwari
Keyword(s):  
Water Droplet ◽  
Supercooled Water ◽  
Freezing Process ◽  
Differential Analysis

Initial-Position-Driven Opposite Directional Transport of Water Droplet on Wedge-Shaped Groove

Nanoscale ◽  
2021 ◽  
Author(s):  
Shaoqian Hao ◽  
Xie Zhang ◽  
Zheng Li ◽  
Jianlong Kou ◽  
Fengmin Wu
Keyword(s):  
Water Droplet ◽  
Initial Position ◽  
Water Droplets ◽  
Transport Direction ◽  
Directional Transport ◽  
Prevailing View ◽  
Functionalized Surface

Transport direction of water droplets on a functionalized surface is of great significance due to its wide applications in microfluidics technology. The prevailing view is that a water droplet on...

scholarly journals Simulation of Thermal and Electric Field Distribution in Packaged Sausages Heated in a Stationary Versus a Rotating Microwave Oven

Foods ◽  
2021 ◽  
Vol 10 (7) ◽  
pp. 1622
Author(s):  
Wipawee Tepnatim ◽  
Witchuda Daud ◽  
Pitiya Kamonpatana
Keyword(s):  
Temperature Distribution ◽  
Electric Field ◽  
Three Dimensional ◽  
Development Stage ◽  
Microwave Oven ◽  
Computational Time ◽  
Plastic Package ◽  
Heating Uniformity ◽  
The Cost ◽  
Good Agreement

The microwave oven has become a standard appliance to reheat or cook meals in households and convenience stores. However, the main problem of microwave heating is the non-uniform temperature distribution, which may affect food quality and health safety. A three-dimensional mathematical model was developed to simulate the temperature distribution of four ready-to-eat sausages in a plastic package in a stationary versus a rotating microwave oven, and the model was validated experimentally. COMSOL software was applied to predict sausage temperatures at different orientations for the stationary microwave model, whereas COMSOL and COMSOL in combination with MATLAB software were used for a rotating microwave model. A sausage orientation at 135° with the waveguide was similar to that using the rotating microwave model regarding uniform thermal and electric field distributions. Both rotating models provided good agreement between the predicted and actual values and had greater precision than the stationary model. In addition, the computational time using COMSOL in combination with MATLAB was reduced by 60% compared to COMSOL alone. Consequently, the models could assist food producers and associations in designing packaging materials to prevent leakage of the packaging compound, developing new products and applications to improve product heating uniformity, and reducing the cost and time of the research and development stage.

scholarly journals Influence of Substrate Material on Flow in Freezing Water Droplets—An Experimental Study

Water ◽  
2021 ◽  
Vol 13 (12) ◽  
pp. 1628
Author(s):  
Erik Fagerström ◽  
Anna-Lena Ljung ◽  
Linn Karlsson ◽  
Henrik Lycksam
Keyword(s):  
Turbine Blades ◽  
Maximum Velocity ◽  
Substrate Material ◽  
The Arctic ◽  
Natural Phenomenon ◽  
Contact Radius ◽  
Freezing Process ◽  
Water Droplets ◽  
Symmetry Line ◽  
Influence Of Substrate

Freezing water droplets are a natural phenomenon that occurs regularly in the Arctic climate. It affects areas such as aircrafts, wind turbine blades and roads, where it can be a safety issue. To further scrutinize the freezing process, the main objective of this paper is to experimentally examine the influence of substrate material on the internal flow of a water droplet. The secondary goal is to reduce uncertainties in the freezing process by decreasing the randomness of the droplet size and form by introducing a groove in the substrate material. Copper, aluminium and steel was chosen due to their differences in thermal conductivities. Measurements were performed with Particle Image Velociometry (PIV) to be able to analyse the velocity field inside the droplet during the freezing process. During the investigation for the secondary goal, it could be seen that by introducing a groove in the substrate material, the contact radius could be controlled with a standard deviation of 0.85%. For the main objective, the velocity profile was investigated during different stages of the freezing process. Five points along the symmetry line of the droplet were compared and copper, which also has the highest thermal conductivity, showed the highest internal velocity. The difference between aluminium and steel was in their turn more difficult to distinguish, since the maximum velocity switched between the two materials along the symmetry line.

Numerical investigation of the impacting and freezing process of a single supercooled water droplet

2021 ◽  
Vol 33 (4) ◽  
pp. 042114
Author(s):  
Yongkui Wang ◽  
Lei Ju ◽  
Duanfeng Han ◽  
Qing Wang
Keyword(s):  
Numerical Investigation ◽  
Water Droplet ◽  
Supercooled Water ◽  
Freezing Process

scholarly journals Heterogeneous freezing of water droplets containing kaolinite particles

2011 ◽  
Vol 11 (9) ◽  
pp. 4191-4207 ◽  
Author(s):  
B. J. Murray ◽  
S. L. Broadley ◽  
T. W. Wilson ◽  
J. D. Atkinson ◽  
R. H. Wills
Keyword(s):  
Cooling Rate ◽  
Surface Area ◽  
Clay Mineral ◽  
Constant Temperature ◽  
Hydrophobic Surface ◽  
Supercooled Liquid ◽  
Stochastic Approach ◽  
Solid Particles ◽  
Rate Coefficients ◽  
Water Droplets

Abstract. Clouds composed of both ice particles and supercooled liquid water droplets exist at temperatures above ~236 K. These mixed phase clouds, which strongly impact climate, are very sensitive to the presence of solid particles that can catalyse freezing. In this paper we describe experiments to determine the conditions at which the clay mineral kaolinite nucleates ice when immersed within water droplets. These are the first immersion mode experiments in which the ice nucleating ability of kaolinite has been determined as a function of clay surface area, cooling rate and also at constant temperatures. Water droplets containing a known amount of clay mineral were supported on a hydrophobic surface and cooled at rates of between 0.8 and 10 K min−1 or held at constant sub-zero temperatures. The time and temperature at which individual 10–50 μm diameter droplets froze were determined by optical microscopy. For a cooling rate of 10 K min−1, the median nucleation temperature of 10–40 μm diameter droplets increased from close to the homogeneous nucleation limit (236 K) to 240.8 ± 0.6 K as the concentration of kaolinite in the droplets was increased from 0.005 wt% to 1 wt%. This data shows that the probability of freezing scales with surface area of the kaolinite inclusions. We also show that at a constant temperature the number of liquid droplets decreases exponentially as they freeze over time. The constant cooling rate experiments are consistent with the stochastic, singular and modified singular descriptions of heterogeneous nucleation; however, freezing during cooling and at constant temperature can be reconciled best with the stochastic approach. We report temperature dependent nucleation rate coefficients (nucleation events per unit time per unit area) for kaolinite and present a general parameterisation for immersion nucleation which may be suitable for cloud modelling once nucleation by other important ice nucleating species is quantified in the future.

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