Using heat of solution of aluminum sulfate to store energy in tankless vacuum-tube solar water heaters

Patent metadata

Field	Value
Publication number	US-9890314-B2
Application number	US-201414551363-A
Country	US
Kind code	B2
Filing date	Nov 24, 2014
Priority date	Nov 24, 2014
Publication date	Feb 13, 2018
Grant date	Feb 13, 2018

Abstract

The present invention generally relates to solar water heaters, in particular to solar water heaters using glass vacuum tubes as both solar energy collector and thermal energy storage device, without a hot water storage tank. To improve the efficiency of thermal energy storage, a novel medium for thermal energy storage is disclosed, which utilizes the heat of solution of aluminum sulphate, comprising water and 40% to 47% of Al 2 (SO 4 ) 3 . The working temperature range of such energy storage medium is between 50° C. and 100° C. The energy storage medium is contained in plastic capsules, submerged in water and placed in glass vacuum tubes.

First claim

What is claimed is:

1. A solar water heater using comprising:
at least one glass vacuum tube having an evacuated space between an inner wall and an outer wall to collect solar radiation and to store thermal energy using a thermal energy storage medium comprising water and 40% to 47% of Al 2 (SO 4 ) 3 ;
wherein said thermal energy storage medium is contained in plastic capsules;
a conduit extending into said glass vacuum tube defining an inner flow path, having an open end directing water to be heated by said solar water heater from said conduit to the bottom of said glass vacuum tube;
an outer flow path between said conduit and said inner wall, said outer flow path being coaxial with and counter to said inner flow path;
wherein said plastic capsules are contained in said outer flow path;
wherein after exiting said conduit, water is directed through said outer flow path and between said plastic capsules, wherein heat is transferred directly from said plastic capsules to said water to be heated by said solar water heater; and
at least one gasket in contact with said inner wall, said gasket providing a seal against said inner wall and preventing fluid flow therebetween.

2. The apparatus of claim 1 wherein the inner diameter of said glass vacuum tubes is between 80 mm and 120 mm.

3. The apparatus of claim 1 wherein the said capsules are made of plastics with working temperature higher than 100° C. including polypropylene homopolymer or high density polyethylene.

4. The apparatus of claim 1 wherein the shape of the capsules are tubes of various types of cross sections wherein the distance from each point inside the capsules to the nearest capsule surface is less than 10 mm.

5. The apparatus of claim 1 wherein the capsules are filled with said mixture of water and Al 2 (SO 4 ) 3 at a high temperature when the said mixture is pure liquid.

6. The apparatus of claim 1 wherein the capsules are filled with the said mixture of water and Al 2 (SO 4 ) 3 using an automatic machine, and then a cap of the capsule is sealed after filled.

7. A water handling apparatus to transfer the thermal energy inside glass vacuum tubes of claim 1 to running water comprises:
a horizontal hot-water chamber of rectangular cross section with side dimensions 50 mm to 75 mm and length determined by the product of the number of vacuum tubes multiplied by the sum of the outer diameter of the vacuum tube and a spacing of 3 mm to 10 mm;
a number of vertical tubes connected to the lower side of the said hot-water chamber,
each said vertical tube has one or more gaskets fitted to the outside of the said vertical tube, each said gasket is designed to seal against the inner surface of a said glass vacuum tube;
a thermal insulation cage enclosing the said hot-water chamber;
a horizontal cold water pipe of diameter 10 mm to 25 mm inside the said hot-water chamber;
a number of vertical cold-water pipes connected to the said horizontal cold-water pipe, which extends through each said horizontal tube to reach the bottom of each said glass vacuum tube;
one or more outlet pipes at the high end of the said hot-water chamber for steam escape;
a cold-water supply chamber comprising a fill valve receiving cold water from the running water supply and connected to the hot-water chamber through the said horizontal cold-water pipe to control the water level such that the water level in the said hot-water chamber is half filled;
a hot-water pipe from the lower end of the said hot-water chamber connected to the hot-water inlet of a thermostatic mixing valve, and the cold-water inlet of the said thermostatic mixing valve is connected to the source of running cold water, such that the temperature of the warm water from the outlet of the said thermostatic mixing valve remains constant.

8. The apparatus of claim 7 wherein the said hot-water chamber and said tubes and pipes are made of plastics with working temperature higher than 100° C. including but not limited to polypropylene homopolymer.

9. The apparatus of claim 7 wherein the said hot-water pipe outside the said hot-water chamber is insulated with foam plastics including but not limited to polyurethane.

10. The apparatus of claim 7 wherein the said gaskets are made of silicone elastomer.

11. The apparatus of claim 7 wherein the said gaskets are made of nitrile butadiene rubber.

Assignees

• Univ Columbia

Inventors

• Chen Chengjun Julian

Classifications

• F28D20/02

  using latent heat · CPC title

• C09K5/063 Primary

  Materials absorbing or liberating heat during crystallisation; Heat storage materials · CPC title

• F24S10/45

  the enclosure being cylindrical · CPC title

• F28D2020/0021

  the heat storage material being enclosed in loose or stacked elements · CPC title

• Y02E70/30

  Systems combining energy storage with energy generation of non-fossil origin · CPC title