Micro Turbines in Maritime Transportation

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Hello! Or should I say, welcome aboard! In this edition of micro gas turbines in transportation, we’re going to be looking at micro gas turbines in the marine world. Marine transportation presents its own set of unique challenges not seen in other forms of transportation; although some of the common challenges and hurdles will be seen here too. If you haven’t read the other entries, or the introduction, I highly recommend you do so here.

Out of all the different vehicles and forms of transportation that will be covered in this series, the boat as we know it is one of the oldest ways of getting about. From rowing to sailing to paddle wheels and engines, the boat has a long history of carrying every kind of good and being imaginable. Much like the topic of turbines, marine transportation can take up oceans of information; in fact you might say that it’s a whale of a topic.

Whale Whale Whale
Whale, here we are with another pun. I hope it brightens your day at least! Image courtesy of The Georgia Aquarium

This blog will specifically cover a brief history of motorized marine transportation, where/how micro turbines can be used, and the inherent advantages and disadvantages. Let’s get started!

A Brief History of Engines in Marine Transportation

Steamboats became popular in the 19th Century when the Industrial Revolution was in its early stages. Steam engines like the ones designed by James Watt were used to propel everything from small riverboats like the ones that went up and down the Missouri river, to oceangoing steamships. The engines typically drove a propeller or “screw” or a large paddle wheel like what is commonly seen on a watermill. Different steam engines in different configurations dominated marine transportation throughout the 19th century, and by the turn of the 20th century, large expansion engines began to be utilized for oceangoing ships like the Olympic-class ocean liners as well as warships. Read More

Turbomachinery System and Component Training: Something for Everyone!

Mechanical engineering is an ever-changing field, and we want to be there to help engineers stay ahead of the curve, even while they are flattening it. In that spirit, we wanted to share with you our different training options that are available now. Whether you are looking to brush up on the fundamentals, or evaluate a software platform, this is a great time to train and explore the latest and greatest in turbomachinery engineering.

Without further ado, let’s get into it!

Private Corporate Trainings Online

First and foremost, the best most comprehensive training you can get from SoftInWay is a private session with one of SoftInWay’s lead engineers and your team. Why is this the best training option? A couple of reasons:

  • Courses are entirely customizable: The scope of these private training courses is tailored to your specific needs. Are you looking to learn the fundamentals? Or perhaps you want to expand your team’s R&D capabilities when it comes to turbomachinery, rotor dynamics, and 1D thermal systems? Whatever the application, we’ll work with you to develop a course curriculum which brings the most value to you and your team.
  • One-on-one consultation with our expert engineers on individual projects and challenges. Our engineering expertise ranges from flowpath design on a turbomachine, to rotor dynamics, as well as secondary flows/multiphase flows, and other all-encompassing projects such as liquid rocket engine design.
  • ll registrants get a 1-month license of the relevant AxSTREAM modules. During the class, users will be familiarized with the ins and outs of AxSTREAM, and be able to make use of AxSTREAM’s capabilities for 1 month afterwards.

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The class can be as long or as short as you need and scheduled around you and your team. Read More

An Introduction to Shock Waves

When you think of shock waves, I would wager that you picture a supersonic jet zooming past overhead. Or maybe you have experienced the famous (or infamous) “sonic boom” that accompanies shock waves attached to airplane engines. The engineering challenges associated with the often-troublesome behavior of shock waves is present in all scales, from carefully designing the bodywork of the aforementioned fighter jets, to the equally intricate details of flow passages and blade design in turbomachinery. The first step in taking into account the effect of shock waves is to understand what they are. In this post we will be reviewing a short introduction into what shock waves are and a few applications where they might be relevant.

Figure 1: Schlieren image showing the shock waves of a supersonic jet
Figure 1: Schlieren image showing the shock waves of a supersonic jet. Source

What are shock waves?

Shockwaves are non-isentropic pressure perturbations of finite amplitude and from the second law of thermodynamics we can say that shockwaves only form when the Mach number of the flow is larger than 1. We can distinguish between normal shocks and oblique shocks. In normal shocks, total temperature is constant across the shock, total pressure decreases and static temperature and pressure both increase. Across oblique shocks, flow direction changes in addition to pressure rise and velocity decrease. Read More

Cooling Methods in Turbine Blades

Turbine components are placed right after the combustor and are therefore, subject to the highest temperatures in an engine. The turbine blades are directly in the line of fire (so to speak) of these incredibly high temperatures. Higher temperatures yield higher cycle efficiencies, meaning that the limit on efficiency for a cycle is determined by turbine materials. The current state of the art materials can only give so much heat resistance capacity, which makes blade cooling essential. In this post we’ll be taking a look at the various cooling methods that exist for turbine blades, and the tools to design them.

Figure 1: High pressure turbine guide vane with cooling holes
Figure 1: High pressure turbine guide vane with cooling holes. Source

How important is cooling to the efficiency of gas turbine engines?

In a word, very.  Let’s look at an example to better explain.  Our fictitious engine without cooling has an overall pressure ratio of 40 where the maximum allowable turbine entry temperature (TET) is at 1498 K, yielding a thermal efficiency of 33%. When compared to a turbine with cooling, TET can be increased to 1850 K, yielding a thermal efficiency of 38%. This is an 8% increase in efficiency via the addition of cooling. In order to achieve good thermal efficiency in our cycles, turbine components must be cooled!

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Basics of Steam Turbine Design

Steam turbines account for more than half of the world’s electricity production in power plants around the world and will continue to be the dominant force in electricity power generation for the foreseeable future. The enhancement of steam turbine efficiency is increasingly important as the urgency to reduce CO2 emissions into the atmosphere is a problem at the forefront of power production. Increasing efficiency in steam turbines, and other components of power plants, will help meet the growing demands for electricity worldwide while reducing harmful greenhouse emissions.

Figure 1 Steam Turbine with Long Last-Stage Blades
Figure 1. Steam Turbine with Long Last-Stage Blades. Source

Steam turbines are used in coal-fired, nuclear, geothermal, natural gas-fired, and solar thermal power plants. Also steam turbines are increasingly needed to stabilize fluctuating power demands from solar and wind power stations as renewable energy sources grow worldwide. The current emphasis on steam turbine development is for increasing efficiency, mainly by increasing steam turbine capacity, as well as increasing operational availability, which translates to rapid start up and shut down procedures.  Read More

Vapor-Compression Refrigeration Systems

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.

Schematic of Refridgeration System in AxSTREAM NET
Figure 1. Modern-day Refrigeration System in AxSTREAM NET
Introduction

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?

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Pump Performance Improvement Using AxSTREAM ION

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.

Redesign Pump with Smooth Beta and Theta Distributions
Figure 1. Centrifugal Pump in AxSTREAM

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.).
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Series on Micro Gas Turbines And How They Can Make the World Greener

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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!

Micro Gas Turbine and Corgi
Figure 1: A micro gas turbine with a pencil for scale (left) and your average corgi (right). Not very aerodynamic, but awfully cute. Source

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).

Figure 3: A commercial airliner's turbofan engine the common image that is conjured when one thinks of turbines in transportation
Figure 3: A commercial airliner’s turbofan engine; the common image that is conjured when one thinks of turbines in transportation.
History

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.

Micro Turbine Compressor
Figure 4: A micro turbine compressor model.

 

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.

Advantages: 

  • – 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)

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Disadvantages:

  • – 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

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A Micro Gas Turbine
Figure 5: A Microturbine
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

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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 info@softinway.com

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Choosing the Right Turbomachinery Component

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.

Large thermal power machine

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

Thermal Management in Aerospace Electric Propulsion Systems

The growing interest towards electric propulsion system for various applications in aerospace industry is driven first by the ambitious carbon emissions and external noise reduction targets. An electric propulsion (EP) system not only helps reduce the carbon emissions and external noise, but also helps reduce operating cost, fuel consumption and increases safety levels, performance and efficiency of the overall propulsion system. However, the introduction of electric propulsion system leads engineers to account for certain key challenges such as electric energy storage capabilities, electric system weight, heat generated by the electric components, safety, and reliability, etc. The available electric power capacity on board may be one of the major limitations of EP, when compared with a conventional propulsion system. This may be the reason electric propulsion is not the default propulsion system. Now, let’s consider how electric propulsion is used in the aerospace industry. Following the hybridization or complete electrification strategy of the electric drive pursued on terrestrial vehicles, the aerospace industry is giving great attention to the application of electrical technology and power electronics for aircrafts.

Figure 1 Aircraft Electric Propulsion Architectures
Figure 1. Aircraft Electric Propulsion Architectures. SOURCE: [1]
Electric Propulsion in aircrafts may be able to reduce carbon emissions, but only if new technologies attain the specific power, weight, and reliability required for a successful flight. Six different aircraft electric propulsion architectures are shown in Figure 1, above, one is all-electric, three are hybrid electric, and two are turbo-electric.  These architectures, rely on different electric technologies (batteries, motors, generators, etc.).

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