Although crossover design has only a secondary effect on pump efficiency, it too should use every available trick to achieve the best possible results.
This picture (left and below) shows short and long configurations of the two basic types of crossovers normally used on multi-stage pumps. Both have been tested by the West Coast pump companies and the results of these tests indicate that the radial diffusion type is approximately one point more efficient than the diagonal diffusion type. Here’s why: Continue reading “Radial versus Diagonal Diffusion in Multi-Stage Pumps”→
We all know by now that no machine is perfect. Turbines have carryover losses, pumps experience cavitation phenomena, and compressors certainly have their fair share of pros and cons. We’re on the hunt for some common design problems – perhaps problems that you have experienced yourself, with centrifugal compressors. We scoured through our technical papers and presentations and searched the web for some. Here’s a list of frequent concerns and questions we ran into: Continue reading “Let’s Talk About Centrifugal Compressors”→
Organic Rankine Cycle (ORC) is a technology that can convert thermal energy at relatively low temperatures (80 to 350°C or 175 to 660°F) to actual work that can be further converted into electricity.
It is basically a thermodynamic cycle according to the Rankine principle but specifically uses organic fluids in order to have a boiling point at relatively low temperatures.
The heat is used to make the liquid boil and generate high pressure gases that will then drive equipment able to transmit torque to the shaft and create electrical power.
There are two main types of machines that are able to do this
• Turbine-based system
• Reciprocating piston-based system Continue reading “Components of an ORC Cycle”→
Cavitation is not welcome in pumps. One of the most problematic effects of cavitation is the reduction in performance, but this is not the only problem! Cavitation can also cause damage to blades and create noise while the pump is working.
Perhaps, the most universal problem caused by cavitation is the material damage that bubbles can cause when they collapse in the vicinity of a solid surface. The problem is complex because it involves the details of a complicated unsteady flow combined with the reaction of the particular blade material. Continue reading “Cavitation Problems”→
Unlike the centrifugal pump, the performance in axial machines is a function of the action of the blade profiles. Because of this, the main approach in design of axial pumps is focused on blade performance.
Impeller blades of axial flow pumps have a double curvature form at the inlet and at the outlet due to the change in diameter from hub to periphery. Absolute flow before and after the impeller and relative flow along the impeller passage are axisymmetric and potential. There is no radial mixing. Under this condition, each streamline is parallel to the axis of the pump. Fluid passes parallel to the pump axis i.e., along the streamline. Continue reading “Axial and Mixed Pump Theory”→
We had a great week last week with our Steam and Gas Turbine Design workshop and we thank all of our participants who joined us in Boston and Zug, Switzerland! But like any rotating turbomachinery company, we’re rotating right along into another topic, pumps.
As with any turbomachine, when you’re in the process of selection, you should take into account a few factors depending on the application.
A number of loss prediction methods exist in turbomachines. Concerning axial turbines, there are at least seven methods just for cascade losses! But there are also loss models developed to predict individual loss components such as secondary, seal and tip clearance losses and more.
Of course depending on the machine and application type, some of the models are more or less applicable to specific cases. But ff the different types of auxiliary losses, which are losses that do not belong to blade cascades and can be classified as whole stage, there are carryover losses.