EPA Imposes Stringent Emission Levels From Engines

EPA emission levelsRecently the Environmental Protection Agency (EPA) imposed more stringent emission levels from engines. These emission restrictions are expected to increase (lower levels) in the near future. As such, modern engine designs, inevitably will need to meet the goal of ultra clean combustion. Different pollutants are emitted due to incomplete combustion, like unburned hydrocarbons (UHC), carbon monoxide (CO), nitrogen oxides (NOx), sulfur oxides (SOx), and black carbon (BC) — also known as soot. The environmental impact of each of these pollutants is well known and can range from reduced visibility due to smog and cloud formation to cancer and premature death when inhaled by respiratory system. Continue reading

Modeling Waves to Keep the Sea Clean

In 2013, over 4400 million tonnes of crude oil was extracted, which caters to roughly 33% of the global need for energy. Most of this oil is extracted from offshore sites and transported to shores for further processing. During this production and transport, if an accidental release of the crude or processed oil occurs, it is called Oil Spill. With the advancement of technology, volumes of oil spilled have reduced over last few decades, however, factors of human error and natural calamity can never be completely ruled out. Continue reading

Collaborating to Reduce Gas Turbine Fuel Burn

The pressure is on to reduce fuel burn for gas turbines of all types. The need is particularly acute for aircraft engines, in that fuel is a large component of operating costs of an airline, so much so that even the volatility in its price can mean the difference between profit and loss. So when airlines demand more fuel efficient aircraft, much of that requirement is passed along to the engine manufacturers. While reducing gas turbine fuel burn is a primary driver, carbon emissions are related, so reducing the fuel burn “kills two birds with one stone”. Continue reading

The Tenth Drop in the Pitch Drop Experiment

image of pitch drop experiment

The pitch drop experiment
© Image published with the permission of the University of Queensland

The Pitch drop experiment was initiated in 1927 at the University of Queensland, Australia. It consists of observing the very slow flow of a highly viscous material through a convergent, under gravity effect. In this experiment, one drop grows and falls within about a decade.

The ninth drop has fallen in April 2014; it needed about 14 years to grow and fall. One may wonder when the tenth drop will fall. Although the key material property, the viscosity, is difficult to measure, it is possible to perform a numerical simulation with ANSYS POLYFLOW software. The very long time interval involved in the experiment suggests using the month as time unit, instead of the second as is usually the case for transient cases. Of course, this requires converting the physical data accordingly. The calculation involves not only the motion of the drop from the conical reservoir into the channel; it also incorporates the development of the pitch drop under the channel exit; this is an important ingredient to the mechanism of the drop formation. Continue reading

Improving Performance and Durability of Heat Exchangers

image of heat exchangers with vapor volume fraction

Vapor Volume Fraction in EGR Cooler Due to Boiling

Heat exchangers are among the most common process equipment. They come in different sizes (e.g. cold plate within your mobile phone vs a waste heat recovery system in a plant), shapes (shell and tube, tube in tube, plate and frame, for example) and types (recuperative and regenerative).

Although many heat exchangers have been thoroughly studied, analyzed and even optimized, the need to improve heat exchanger performance, reduce their capital and running costs, and increase their durability will never end. Continue reading

Coupling Piezoelectric and Fluid Simulations

ink jet nozzle

Ink jet nozzle

Piezoelectric devices surround us in our everyday life. Our cars and trucks contain many piezoelectric devices, including fuel level sensors, air bag deployment sensors, parking sensors and piezoelectric generators in the wheels to power the tire pressure monitoring system. Your smartphones or tablet contains piezoelectric sensors that detect the motion and orientation of the device, which my kids were using to good effect to play “Need For Speed” yesterday. Many of us have ink jet printers at home, which can use piezoelectric printer heads to eject thousands of drops per second. Continue reading

How Bioreactors Are Keeping Cells Happy

image of mixing tank velocity surface cell bioreactor

Velocity iso-surface colored by Eddy viscosity

Cell-culture bioreactors lie at the heart of the processes used to produce large-molecule, protein-based therapeutics. In cell culture, mammalian cells are grown outside the human/plant body. These cells produce therapeutic proteins and antibodies. This is much easier said than done. In fact, cells do not cooperate much when they are grown outside the (human or plant) body. The question then is: Why is it so difficult for cells in culture to have the same physiological function in laboratory as in our body? Continue reading

Using CHEMKIN Simulation Software for Complex Chemical Processes

As a new member of the ANSYS family, via the Reaction Design acquisition, I thought I would take the opportunity to give you a little background on the product line I represent — CHEMKIN.

The software had its beginnings at Sandia National Laboratories, as part of the U.S. Government’s response to the oil crisis of the 1970s. Scientists at Sandia began studying how to make more efficient, cleaner-burning engines, and they created software to simulate the complex molecular-level chemical reactions that take place during fuel combustion. In 1997, Reaction Design licensed that software from Sandia and evolved the technology into a commercial-quality software suite that enables engineers and scientists in microelectronics, combustion and chemical processing industries to develop a comprehensive understanding of chemical processes and kinetics. Continue reading