Abstract: A hybrid condenser or fluid cooler having an indirect heat exchange and a direct heat exchanger, in which tube circuits in the indirect heat exchanger are arranged parallel to the direction of air flow of a crossflow direct heat exchanger. The design features elongated fluid headers combined with multiple shortened circuits, resulting in a compact design that lowers the fluid pressure drop across the heat exchanger. This design creates an increased turbulence in relation to fluid flow, resulting in an increase in thermal performance.

Abstract: A method for obtaining a baseline for detecting rotating stall using localized information already included within the frequency spectrum. Namely, ratiometric measures, i.e., quadratic coefficients obtained from weighted quadratic regression of sub-synchronous spectrum and/or information obtained through peak detections, are used to detect rotating stall. These ratiometric measures are configured to isolate changes caused by rotating stall from those caused by other operational conditions. As a result, new baseline information can be established to more reliably characterize a system, such as a system with associated turbines or compressors. Empirical or statistical approaches can be combined to automate the process of obtaining a new baseline and to detect rotating stall.

Abstract: A method for obtaining a baseline for detecting rotating stall using localized information already included within the frequency spectrum. Namely, ratiometric measures, i.e., quadratic coefficients obtained from weighted quadratic regression of sub-synchronous spectrum and/or information obtained through peak detections, are used to detect rotating stall. These ratiometric measures are configured to isolate changes caused by rotating stall from those caused by other operational conditions. As a result, new baseline information can be established to more reliably characterize a system, such as a system with associated turbines or compressors. Empirical or statistical approaches can be combined to automate the process of obtaining a new baseline and to detect rotating stall.

Abstract: A dimension sensor is used in conjunction with a tube and includes a body member and at least one detector element. The body member has an inner surface defining an opening sized to receive the tube. The at least one detector element is connected to the body member and has a detector portion extending into the opening. When the tube is received in the opening, the detector portion is initially disposed apart from the tube. A method using the dimension sensor stops expansion of the tube expanding from a pre-expanded state to a desired expanded state. A pumping device is actuated to pressurize a fluid by an amount sufficient to cause the tube to expand from the pre-expanded state to the desired expanded state. When the tube expands to the desired expanded state, the pumping device deactivates thereby stopping expansion of the tube at the desired expanded state.