Hydraulically-Opened Cone Vertical Tube Diffuser with Slanted Anti-Siphon Hole

Summary

Hot water heaters typically show a reduction of water temperature during long periods of use. First-hour rating (FHR), the industry metric that captures the ability of hot-water tanks to deliver hot water for long periods, needs to be increased to accommodate longer periods of hot water availability. This invention, a hydraulically opened cone vertical tube diffuser with a slanted anti-siphon hole, increases the FHR of hot-water tanks by reducing the mixing near the vertical tube inlet (VTI) in the hot water tank.

Description

To increase the FHR, the mixing at the bottom of the tank is reduced by slowing the velocity of the flow through a diffuser. Common Vertical Tube Inlets (VTIs) do not expand the cross-section of the tube as the tube must fit through a smaller hole at the top of the tank. To fit through the hole at the top of the tank, the cone structure needs to be collapsible. The cone is held open by these jets coming out of the holes during a hot-water draw, and the water is then pushed downwards at a slower velocity through the larger cross-sectional area. Any modification to the VTI shape or installing the VTI too close to the bottom of the tank creates back-pressure upstream of the VTI diffuser, which results in cold-water coming out of the anti-siphon hole. To alleviate this, we angle the anti-siphon hole to reduce the chances of cold-water flowing out from the VTI. This diffuser keeps hot water from mixing with cold by slowing down the viscosity inside the tank, which is what decreases the amount of hot water available over time. The shape also allows it to do so in an organized way. For the VTI to reduce turbulence, it must be fully expanded inside the tank, so we improved the structure holding the diffuser open. Also, there is an anti-siphon hole at the top of all VTIs for safety reasons. Water comes out of this hole when there is back-pressure developed at the outlet of the VTI. Diffusers create significant back-pressure, so this provides a solution at the anti-siphon hole as well. The overall result is longer periods of hot water.

Applications and Industries

• Home-building industry
• Large commercial users of hot water, i.e., university campuses
• Anywhere hot water storage is required

Benefits

• Longer periods of hot water use
• Increased first-hour rating of hot-water tanks
• Prevents hot and cold water mixing, increasing hot water availability