DK178002B1 - Heat exchanger - for the recovery of residual heat in wastewater from showers - Google Patents

Abstract

Heat exchanger for heat recovery from the waste water from the shower, comprising a helical drain pipe, which is placed in a container which is insulated and has cold water tap water in the bottom and outlet of preheated water at the top, characterized in that the helical drain pipe is made in copper with a decrease of approx. 12%, and that the container is made with a central filling. The outside of the helical drain can be provided with ribs for increasing the heat exchange between the hot sewage inside the drain and the cold waterworks outside. The heat exchanger may further comprise an activatable, flexible constriction on the outlet at the bottom, which can either be activated via pressure drop in the waterworks water, so that there is full outlet when the drained water is drained off, or via wastewater recovery, so that the effluent outlet is reduced as long as the wastewater temperature exceeds a predetermined value.

Description

Heat exchanger - for heat recovery of residual heat in wastewater from shower.

About half of Denmark's energy consumption goes to heating and operating homes. There are clear political signals, and specific laws, which are intended to reduce energy consumption in the housing stock, have already been adopted.

Measures and techniques that can reduce energy consumption in the housing stock have become extra relevant ifm. The Climate Conference 2009, and new stricter requirements in the Building Regulations regarding energy consumption. With the already existing regulations, and not least if you look at low-energy houses, then the proportion of energy consumption that goes to the production of hot consumable water constitutes a very significant proportion of the total energy consumption of homes. Recent calculations show that the energy for hot water production in an energy class 2 house is the same size as the energy to be used for heating the house. It is therefore obvious to see how the energy consumption for this can be reduced, optimized or provided via new channels.

DK 1999 00285 U3 shows a heat exchanger for the recovery of heat from wastewater. Inside a container part is arranged a helical heat exchanger, which is provided with an upper and a lower pipe connection in the container part. The helical heat exchanger is connected with cold utility water, which is fed into the upper part of the container and discharged below, while the hot drainage water is passed through the container part outside the helical heat exchanger.

DE 19817031 A1 shows a heat exchanger in which a helical drain pipe is arranged internally in another helical outer pipe connection, so that the drain water can move up and down the drain pipe while the utility water to be heated moves countercurrently from below and up into the cavity inner and outer helical tubular connection. Such a construction is quite complicated to manufacture, and very difficult (if not directly impossible) to clean once it has been installed and put into service.

As more than 60% of all hot water in a household goes to baths and an average of 850 kWh is used per day. person for heating hot water, disappears approx. 500 kWh per person into the drain a year on that account.

If you can find a way to recover some of the heat that disappears with the spent shower water in the drain, you will be able to save much of the energy that goes into heating domestic water in a household.

The idea is simply to place a heat exchanger, ifm. the floor drain or in the technology room, which preheats the cold waterworks which access the shower or hot water tank.

The heat exchanger is placed after a floor drain that is fitted with a water trap and filter grille. The heat exchanger can be placed if floor drain or central ifm. hot water tank. The thermal energy in the hot wastewater is transferred via a helical drain pipe made of copper, with a decrease of approx. 12%. The helical copper coil is placed in an insulated container which has access to cold tap water at the bottom and outlet of preheated water at the top. The container is filled with a filling in the center, partly to reduce the volume and partly to increase the cold waterworks water, along the helical copper drain - with increasing temperature towards the top. The relatively large drop on the helical copper drain pipe gives a high flow rate, which together with the Coriolis and cintrifugal force '' distributes' the wastewater on a large part of the inner surface of the pipe - resulting in a large heat exchange. The effect may could be increased by providing the helical copper coil with ribs on the exterior ie. in the pure tap water.

Finally, the heat exchange could be increased by delaying the discharge of the wastewater, with a flexible constriction on the outlet at the bottom. This one could possibly. is activated via the pressure drop in the waterworks water, so that there is full discharge when the drain is closed. Alternatively, the constriction could be activated via the wastewater heating so that the effluent outlet is reduced as long as there is heat in the wastewater. In both cases, the constriction must not be greater than the full expiration of a maximum drain from the shower.

The attached sketches indicate the principle for the design, which must be optimized according to. the final design. The final design is thought to be done in collaboration with a company that already manufactures drains or drain pipes.

The mode of operation is based on simple well-known physical principles with the exchange of heat from one medium to another, via a good leader. Due. of a very large surface of the heat exchanger (the helical copper coil), an efficiency of more than 50% is expected in terms of heat recovery.

The heat exchanger ifm. floor drains can be used both ifm. new construction and ifm. renovation of bathrooms, primarily ifm. residential. Since the heat exchanger has a relatively modest installation height, it can also be used ifm. bath on l.sal. The heat exchanger for placement in the engineering room will be suitable ifm. new construction, where by careful planning can be placed the bathrooms, so that the drain from the showers can be passed relatively easily to the central heat exchanger. In addition, there are also obvious application possibilities. showers in changing rooms and ifm. hotels and floor properties where the heat exchanger is placed as preheater before the hot water tank.

Since these are partly known old physical principles with the exchange of heat from one medium to another, via a good conductor, the news or invention consists of the following: - the heat exchanger utilizes partial waste heat in used hot shower water, which otherwise simply goes to waste. .

- incorporation of heat exchanger according to floor drain, with simple '' local '' connection in the bathroom, makes it equally suitable ifm. new construction as renovations.

screw-shaped heat exchanger, where the preheating of the water takes place countercurrently to the outlet, so that the heat exchange is increased, the withdrawal of preheated water takes place where the used hot water is fed into the drain, ie. where this is most hot.

- the helical heat exchanger coil is carried out in copper which counteracts biofilm which could otherwise, as an insulating film, reduce the heat exchange. In addition, cooling of the wastewater will also counteract the formation of biofilms which increase with increasing temperature.

Claims (5)

A heat exchanger for heat recovery of residual heat from the wastewater from the shower, comprising a helical drain pipe, which is placed in a container which is insulated and has cold water supply at the bottom and outlet of preheated water at the top, characterized in that the helical drain pipe is made of copper with a decrease of approx. 12%, and that the container is made with a central filling. Heat exchanger according to claim 1, characterized in that the outside of the helical drain line is provided with ribs for increasing the heat exchange between the hot waste water inside the drain pipe and the cold waterworks outside. Heat exchanger according to claim 1 or 2, characterized in that the heat exchanger comprises an activatable, flexible constriction on the outlet at the bottom. Heat exchanger according to claim 3, characterized in that the constriction is activated via pressure drop in the waterworks water, so that there is full outlet when the preheated water is closed. Heat exchanger according to claim 3, characterized in that the constriction is activated via heating from the waste water, so that the effluent outlet is reduced as long as the temperature of the waste water exceeds a predetermined value.