Present day refrigeration is viewed as a necessity to keep our popsicles cold and our perishables fresh. But have you ever wondered what people did to keep their food from spoiling hundreds or even thousands of years ago? Or just what goes into a refrigerator system today? In this blog, we’ll take a look at how refrigeration works; the history behind it; and examine the cycle, working fluids, and components.
Refrigeration is based on the two basic principles of evaporation and condensation. When liquid evaporates it absorbs heat and when liquid condenses, it releases heat. Once you have these principles in mind, understanding how a refrigerator works becomes much more digestible (pun intended). A modern-day refrigerator consists of components such as a condenser, compressor, evaporator and expansion valve, as well as a working fluid (refrigerant). The refrigerant is a liquid which as enters the expansion valve the rapid drop in pressure makes it expand, cool, and turn into a gas. As the refrigerant flows in the evaporator, it absorbs and removes heat from the surrounding. The compressor then compresses (as the name suggests) the fluid, raising its temperature and pressure. From here, the refrigerant flows through the condenser, releasing the heat into the air and cooling the gas back down to a liquid. Finally, the refrigerant enters the expansion valve and the cycle repeats. But what did we do before this technology was available to us?
As pumps have numerous uses, they constitute a significant part of energy consuming equipment. Therefore, pump efficiency plays a significant role in energy savings and operating cost. The design of a centrifugal pump is more challenging to reduce overall cost of the pump and increasing demand for higher performance.
There are two traditional approaches to design a pump for new requirements. One approach is to redesign or modify an existing impeller of centrifugal pump for increasing flow rate/head and efficiency. The modification will also involve selection of different geometric parameters and then optimizing them with the goal of performance improvement in terms of efficiency, increase the head, reduce cross flow and secondary incidence flows. The other approach is to design a pump from the preliminary stage to meet the desired design objectives. Most of the time, the designer knows what they need to achieve (performance target) but the challenge is in how to achieve this target within the given constraints (geometry, cost, manufacturability etc.). Read More
If you’re familiar with turbomachinery, then you probably know the pivotal role they play in our lives. If you’re not, no biggie! Have a look at this blog where I discuss a world without turbomachinery. But where do microturbines fit in? I can’t speak for anyone else, but my mind immediately jumps to turbochargers in small-displacement car engines. There is, however, a whole slew of information, history, and applications for microturbines beyond being a component in your car.
The best place to start, is to establish just what a microturbine is and isn’t. Granted the prefix in the word is a dead giveaway, but just how small is a micro gas turbine? In terms of power output, a micro gas turbine puts out between 25 and 500 kW. The size of these machines varies; some systems can be the size of a refrigerator, while others can fit on your desk. For reference, some of these machines are smaller than your average corgi!
In terms of components, microturbines typically consist of a compressor, combustor, turbine, alternator, generator, and in most machines, a recuperator. While incorporating a recuperator into a microturbine system comes with its own set of challenges, the benefits are often well worth it as efficiency when recuperated hovers around 25-30% (with a waste heat recovery/cogeneration system, efficiency levels can reach up to 85% though).
When and how did the concept of micro gas turbines come about? After the advent of the jet engine in World War II and the prominence of turbochargers being used on piston-driven propeller planes during the war, companies started to see where else gas turbine technology could be utilized. Starting in the 1950’s automotive companies attempted to offer scaled down gas turbines for use in personal cars, and you can read our blog covering that more in-depth here. You can probably guess by the number of gas turbine-powered cars on the road today, that it wasn’t very successful.
Fast forward to the 1970s, companies started to take an interest in micro turbines for stationary power generation on a small, portable scale. Allison developed microturbine-powered generators for the military that showed substantially lower fuel consumption in initial testing. In the 80’s, GRI supported the AES program where they attempted to develop a 50kW turbine for aviation applications, using a heat recovery system to improve efficiency through a cogeneration system. More recently, companies like Capstone have worked with GRI on new projects to introduce microturbines to different industries where they could be useful, using the latest advancements in technology to ensure higher efficiencies and reliability of designs past. To discuss the current state of affairs for microturbines however, it might be good to list some of their present advantages and drawbacks, and then explore where in the world they could be most useful.
Advantages and Disadvantages of Microturbines
As with just about any other type of technology, microturbines have their own set of advantages and disadvantages as a result of their design that are seen in their different applications.
– Lower emissions
– Lower noise level than comparable reciprocating engines
– Fewer moving parts with results in less maintenance needs
– Lower vibration levels
– Ligherweight, compact systems
– Diverse fuel selection (jet fuel, kerosene, diesel, natural gas)
– Very low efficiency without recuperator/waste heat recovery system
– High work requires high speeds (30-120 krpm) for small diameters
– Poor throttle response
– Expensive materials required for manufacturing
– More sensitive to adverse operating conditions
Potential Transportation Industry Applications
There are a number of different industries which microturbines can be found both in and outside of the transportation. Throughout the upcoming months, we’ll be taking a closer look at:
– The Aviation Industry
– The Automotive Industry
– The Marine Industry
– The Rail Industry
Each of these industries has at least one application where micro gas turbine technology has the potential to conserve fuel and lower emissions without compromising power. In the next entry, we’ll look at the current state of the aerospace industry and where/how micro gas turbines can improve upon existing technology.
If you want to learn more about designing a micro gas turbine, or about the tools our engineers and thousands of others around the world rely on for their turbomachinery designs, reach out to us at email@example.com
In our previous blogs we established that rotor dynamicsis a branch of applied mechanics in mechanical engineering and is concerned with the behavior of all rotating equipment, but let’s have a closer look at some of the factors that affect the behavior of rotating equipment.
Here’s a non-exhaustive list of the different static and dynamic forces and phenomena that can act on a rotor train:
– Bearing reaction
– Fluid-rotor interaction
– Impeller aerodynamic loadings
– Misaligned couplings and bearings
– Rubbing between rotating and stationary components
As you can see there’s no shortage of different forces and factors which must be considered to ensure the smooth operation of your turbomachinery and other rotating equipment. While some of these factors are very familiar such as gravity, some factors like rotor unbalance have numerous causes. Here’s another (non-exhaustive) list of different factors that can cause rotor unbalance: Read More
2019 was a year of innovation and exploration for our engineering team as we worked with our customers to develop capabilities both in and outside the realm of turbomachinery. Our dedicated structural and rotor dynamics engineers worked with some of our AxSTREAM RotorDynamics customers to continually develop capabilities to perform torsional forced response analyses in reciprocating compressors. On the thermal-fluid modeling front, our engineers added capabilities to AxSTREAM NET, enabling it to be used for multiphase flows in heat exchangers, rocket engine nozzles, and refrigeration systems, as well as continued development of capabilities for analyzing secondary flows and leakages from turbomachinery flowpaths.
Perhaps one of the biggest buzzwords of the last decade (and for years to come!), SoftInWay’s engineers underwent a project to further streamline the turbomachinery design process leveraging Artificial intelligence (AI). While AxSTREAM ION™ had already made it possible to automate processes in AxSTREAM and enable interaction with external CAD/CAM programs and other commercial/in-house codes, AxSTREAM.AI™ takes it one step further. By utilizing machine learning to iterate designs continually and training the program to recognize feasible and infeasible designs, AxSTREAM.AI™ is able to develop components in just several hours, as opposed to month-long or year-long projects. Read More
In what feels like the blink of an eye, 2019 has come to a close (well, almost). In the last decade, we have seen technology make leaps and bounds with advancements in everything from electric vehicles and propulsion, to artificial intelligence, to the microsatellite industry, and supercritical carbon dioxide (sCO2) power cycles. We’ve even seen the rise of the elusive and mysterious impossible burger. For engineers working in the field of technology as well as the SoftInWay team, it has been an exciting year full of new developments and growth; and we’d love to share a recap of our year with you, our readers!
So what has SoftInWay been up too this year?
Liquid Propulsion Systems Seminar:
Earlier in the year, we hosted a liquid rocket engine design/development seminar in Huntsville Alabama, AKA Rocket City USA. We had a good turnout from companies in the area that included Teledyne Brown, ATA Engineering, as well as other businesses large and small that call the Rocket City home. This event allowed us to show off our latest software development in the aerospace industry, AxSTREAM.SPACE, and how quickly and simply an engineer can design a turbopump for a liquid rocket engine as well as design/optimize the cooling channels in the engine’s nozzle, and perform the rotordynamics analyses for the turbopump.
There is a growing interest in electric and hybrid-electric vehicles propulsion system due to environmental concerns. Efforts are directed towards developing an improved propulsion system for electric and hybrid-electric vehicles (HEVs) for various applications in the automotive industry. The government authorities consider electric vehicles one of several current drive technologies that can be used to achieve the long-term sustainability goals of reducing emissions. Therefore, it is no longer a question of whether vehicles with electric technologies will prevail, but when will they become a part of everyday life on our streets. Electric vehicles (EVs) fall into two main categories: vehicles where an electric motor replaces an internal combustion engine (full-electric) and vehicles which feature an internal combustion engine (ICE) assisted by an electric motor (hybrid-electric or HEVs). All electric vehicles contain large, complex, rechargeable batteries, sometimes called traction batteries, to provide all or a portion of the vehicle’s propelling power.
EVs propulsion system offers several advantages compared to the conventional propulsion systems (petrol or diesel engines). EVs not only help reduce the environmental emissions but also help reduce the external noise, vibration, operating cost, fuel consumption while increasing safety levels, performance and efficiency of the overall propulsion system. However, there are many reasons why EVs and HEVs currently represent such a low share of today’s automotive market. For EVs, the most important factor is their shorter driving range, the lack of recharging infrastructure and recharging time, limited battery life, and a higher initial cost. Though HEVs feature a growing driving range, performance and comfort equivalent or better than internal combustion engine vehicles, their initial cost is higher and the lack of recharging infrastructure is a great barrier for their diffusion. Therefore, industry, government, and academia must strive to overcome the huge barriers that block EVs widespread use: battery energy and power density, battery weight and price, and battery recharging infrastructure. All major manufacturers in the automotive industry are working to overcome all these limitations in the near future.
Common Types of Electric Vehicles
A more universal EVs classifications is carried out based on either the energy converter types used to propel the vehicles or the vehicles power and function . When referring to the energy converter types, by far the most used EVs classification, two big classes are distinguished, as shown in Figure 1, namely: battery electric vehicles (BEVs), also named pure or full-electric vehicle, and hybrid-electric vehicles (HEVs). BEVs use batteries to store the energy that will be transformed into mechanical power by electric motors only, i.e., ICE is not present. In HEVs, propulsion is the result of the combined actions of electric motor and ICE. The different manners in which the hybridization can occur give rise to different architectures such as: series hybrid, parallel hybrid, and series-parallel hybrid. All these different EVs architectures are shown in Figure 2. Read More
Looking into the very near future, tourists traveling into space no longer seems like some fantastic science fiction. The Blue Origin and the Mojave Aerospace Ventures companies are ready to operate their respective manned suborbital spacecrafts in the coming year. While, The Boeing Company and the SpaceX are finishing the certification of their crewed spacecrafts to deliver people at the Low Earth Orbit. This is only the tip of the iceberg in the great competition.
The next ambitious goal of the space industry is to create space hotels (see Figure 1). For example, NASA already has announced opening the ISS for tourists. These objects are long term human habitations and as such have specific requirements for oxygen life support systems (OLSS). If these requirements are not met, people can die. Small variations in the chemical composition of a mixture of the gases all influenced by, pressure, temperature, a humidity and etc. can have disastrous effects. The work of some of these partial system can be analyzed and optimized using AxSTREAM NET™.
Types of life support system of a spacecrafts
The type and complexity of OLSS depends on the duration of the tourists staying in the artificial environment. For example, let’s consider the oxygen life support systems. A hypothetical manned spacecraft has an internal volume 15 m3 (530 ft3) and can carry six space tourists. The amount of the oxygen for the metabolism of one person is 0.830 kg/day (Figure 2). The atmosphere should consists of 19.5 to 23.5 % of an oxygen. Also, the amount of the reserve oxygen should be 0.035 kg (0.077 pounds) per human/hour. If our six space tourists start their journey with the environment gas in the craft at 23.5 % of the oxygen , it will take 3.5 hours to reach critical level. It’s enough time for a suborbital flight, and the oxygen life support system would only be needed as a reserve source. Read More
Hello and welcome to this December edition of the Intro to Rotor Dynamics Blog; and if you’re re-reading this, welcome back! Here are the other entries in this series if you want to retrace our steps thus far:
So now that we’ve covered the basic definition of rotor dynamics and established the consequences of inaccurate/incomplete analyses, let’s look at what standards govern rotor dynamics.
In general, there are several different codes and standards that rotor dynamics engineers look to in order to make machines compliant. The standard they look at for compliance depends on the location of the company, as well as the kind of machine, what industry the company/machines are present in, and what the machine’s application is. With so many different applications, there are many different places to consult in order to make a compliant machine.
So, what are the governing bodies on rotor dynamics and vibration analyses as well as the balancing of rotating machines? Well, there are several
– First, you have the American Petroleum Institute, commonly known as API.
– Next, there’s the International Organization for Standardization, known as ISO.
– There’s also ANSI, the American National Standards Institute.
– Lastly, each company may have internal rules and standards, with their own calculations and tests that are more stringent than the requirements put forth by the other governing bodies.
So where would you find the rules relating to rotor dynamics in the API’s and the ISO’s long lists of standards and regulations? I’m glad you asked.
Traditionally the engineering process starts with Front End Engineering Design (FEED) which is essentially the conceptual design to realize the feasibility of the project and to get an estimate of the investments required. This step is also a precursor to defining the scope for Engineering Procurement and Construction Activities (EPC). Choosing the right EPC consultant is crucial as this shapes the final selection of the equipment in the plant including turbomachinery.
Choosing the right component for the right application is not an easy task. Too many times, one ends up choosing a component that is not the best choice by far. This is quite true when we look at component selections in the process industries compared to those in a power plant where the operating conditions are more or less constant. This improper selection of components is due to multiple reasons such as: insufficient research and studies; limitation of time, resources, budget etc. Read More
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