Off Peaking of electricity consumption for electric heated energy storage
Development of a stratifier, which when installed in an electrical heated water tank, can be used for: Moving electricity usage for heating electrical heated water tanks from peak load periods (e.g. daytime) to off peak (e.g. nights) and reduce heat loss and save electricity as the water tank most often will only be partly heated during the end of the day, and the beginning of the night, when a stratifier is installed.
Project description
A stratifier increases in energy efficiency in a solar circuit as it establishes and maintains the temperature stratification in the hot water tank.The project aims to examine how well a stratifier can create temperature stratification in an electric heated hot water tank. One of the key challenges is whether stratifieren can (designed to) function, even if there is a pump that creates flow.
Works stratifieren also electrically heated tanks are created to:
- Moving electricity consumption for heating of hot water tanks from tip congested periods (peak, eg. The day) to off peak time (eg. Over night)
- Reduce heat loss and save electricity when water tank by installing stratifieren, most often only be partially heated end of the day, in the evening, and only at night. Thus loses the tank less energy overall and saves electricity for heating.
Results
Studies clarified how the temperature stratification is built up during the heating periods in hot water tanks with a vertically positioned electric element, which is inserted into the bottom of the container. Differently shaped stratifier solutions were examined.Laboratory tests showed that a stratifier solution, which consists of a 110 mm steel pipe with a conical top, followed by a PEX pipe with an opening of 20 %, is a good solution, which builds up the thermal stratification in a good way. If the PEX pipe i s replaced with a stratifier consisting of plastic film with a 25 % opening is also a good solution. The PEX pipe was selected as it is a cheaper option than the stratifier in plastic.
The selected stratifier solution allows at the same time the majority of the container can be heated to at least 55 ° C. It is estimated that there is a solid solution with a long life without lime significant problems. The developed stratifier solution will be especially attractive when the variable electricity prices are introduced. The principle of stratifier can be used for the water tanks and storage tanks that can be used to supplement buildings with heating and hot water. Use water storage tanks and storage tank with the developed stratifierløsning can help to ease the transition to the future energy system based on renewable energy. In this context it should be noted that the DHW heating in the future will be even more important than today when buildings heat demand will be reduced.
The stratifier solution is in the project has been testet a experimental set-up with a test container with a height of 1200 mm and a 110 liter hot water tank, which is METRO THERM's most widely used hot water tank. The container including the stratifier solution is suitable for consumers with daily hot water consumption up to approximately 100 l.
The stratifier solution can be improved in several respects and adapted boilers and heat stores of various sizes. It will for example be interesting to investigate how much is gained with other stratifier solutions. It is therefore proposed project to be compared measurement results with CFD (Computational Fluid Dynamics) calculations, and to perform calculations with a validated CFD model for different designs of stratifier. This allows the design of stratifier to be optimized, for example with regard to diameter pipe thickness and material of the pipe around electric element of the funnel shape of the disc opening, PEX pipe diameter and pipe thickness and the design and the number of holes in PEX pipe.
It will also be interesting to investigate how major benefits that can be achieved with intelligent self-learning systems and to examine stratifier solution and their benefits for larger boilers, for example 300 l tanks.
It will also be interesting to investigate how an electric cartridge design and power dissipation per. cm² affect different stratifier solutions suitability and to other applications.
It should also be mentioned that the benefits of the developed probably in many cases may be greater in practice than the calculations suggest, because hot water consumption in practice are often less than anticipated. Therefore the stratifier probably only because of lower heat losses from the hot water tank to be attractive even without variable electricity prices. It would be interesting to conduct studies of the concept in a number of single-family homes to get practical experience.
It is estimated that a market maturation period of 6 months at METRO THERM is realistic.
Key figures
Period:
2014 - 2015
Funding year:
2014
Own financial contribution:
0.27 mio. DKK
Grant:
1.20 mio. DKK
Funding rate:
81 %
Project budget:
1.47 mio. DKK
Category
Oprindelig title
Off peaking af elforbrug til el-opvarmede energilagre
Programme
ELFORSK
Technology
Energy efficiency
Project type
Forskning
Case no.
ELFORSK 346-021
Participants
Danmarks Tekniske Universitet (DTU) (Main Responsible)
Partners and economy
| Partner | Subsidy | Auto financing |
|---|---|---|
| Danmarks Tekniske Universitet (DTU) | ||
| METRO THERM A/S | ||
| EyeCular Technologies Aps |
