NOVELTY - The method involves delivering two-phase bubbly flow to an upper portion of a reservoir (200) above a liquid-vapor interface, where the two-phase bubbly flow of coolant comprises vapor bubbles of coolant dispersed in liquid coolant, and the vapor bubbles condense upon interacting with and transferring heat to amount of liquid coolant in the reservoir. Continuous outlet flow of single-phase liquid is delivered from a lower portion of the reservoir to a pump (20) to provide stable pump operation, where the lower portion is located below a midpoint of the reservoir.    USE - Method for providing continuous flow of single-phase liquid to a pump in a two-phase cooling apparatus to provide stable pump operation for cooling electrical devices e.g. densely packed servers in data centers, personal computers, medical imaging devices, solar panels, high-power diode laser arrays, and electric vehicle components i.e. battery packs, electric motors and power electronics, mechanical devices e.g. turbines, internal combustion engines, radiators, turbochargers, engine intake manifolds, plasma cutters, drills, oil and gas exploratory and recovery equipments, water jet cutters, welding systems, and computer numerical control (CNC) mills or lathes after-treatment components and braking systems, and chemical reactions and/or processes by chemistry equipments e.g. rotary evaporators and reflux distillation condensers.    ADVANTAGE - The method enables utilizing a corrugated tubing to delay onset of slug flow by causing breakdown of larger bubbles into smaller bubbles and causing breakdown of clusters of bubbles due to frictional effects acting on the bubbles when transporting two-phase bubbly flow, and selecting minimal dividing element thickness to provide columnar jet streams and adequate structural integrity for minimizing height of a heat sink module and providing improved freedom when dealing with tight packaging constraints. The method enables reducing a coolant flow rate if bubbles are not visually detected in an outlet chamber of the heat sink module by reducing pump speed, thus reducing energy consumed by the pump and reducing overall energy consumption and operating cost. The method enables facilitating heat rejection from the coolant, so that a heat exchanger allows the reservoir to maintain volume of subcooled liquid that is safely supplied to the pump without risk of vapor lock or instability.    DETAILED DESCRIPTION - An INDEPENDENT CLAIM is also included for a method for providing stable operation of a pump in a two-phase cooling apparatus by condensing two-phase flow upstream of a pump and providing single-phase liquid coolant to the pump to ensure stable pump operation.    DESCRIPTION OF DRAWING(S) - The drawing shows a schematic view of a two-phase cooling apparatus with a pump, a reservoir, a heat exchanger, manifolds of a primary cooling loop, and sections of flexible tubing connecting parallel cooling lines to manifolds to be visible.    Two-phase cooling apparatus (1)    Pump (20)    Heat exchanger (40)    Reservoir (200)    Pressure gauge (255)