To have a successful application of an ORC system, the availability of an adequate heat source is crucial. In principal every heat-generating process, such as burning fossil fuel, can be taken as a heat source for ORC.
However, the aim is to improve energy efficiency and sustainability of new or existing applications with the focus on waste heat and renewable energy sources.
Three sectors have been identified as potential sources for the application of ORC power generation: (more…)
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 (more…)
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. (more…)
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. (more…)
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.
The specific speed should be the first parameter to take into account when designing and installing a new pump. (more…)
In view of the large number of blades in any turbine machine, the existence of unavoidable sources of vibration excitation and the serious consequences of the failure of just one blade, an intimate knowledge and understanding of the vibration characteristics of the blades in their operating environment is essential.
Vibration excitation can arise from a variety of sources but principally involves the following categories: (more…)
Whether it is caused by a “poor” design, extreme operating conditions or even too much deterioration, turbine failures can occur. In order to help prevent these it is necessary to perform regular maintenance on all parts of the machine and control the conditions at which the turbine is operating at any moment in time as well as performing repairs and retrofits to keep the pieces in good shape.
One way to improve steam turbine efficiency is through better seals. However, when designed incorrectly they can create significant damages and performance losses in the turbine. Sealing steam turbine rotors presents several challenges. Any gap between the rotor and the packing lets the steam escape, dropping the pressure and wasting energy. If the packing ring is too tight, however, the rotor will rub, which creates localized hot spots. (more…)
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.