Buffer Tank Heat Pump Layout for Hygienic Low-Return Heating
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Solution Overview
Problem
Existing heating and drinking water systems face a conflict between maintaining hygiene requirements and achieving efficient heat source efficiency, as the return flow temperature from buffer tanks often needs to be kept above 55°C to prevent bacterial growth, which contradicts the desire for low return flow temperatures to maximize heat source efficiency.
Innovation Solution
A buffer tank with an integrated heat pump, where the warm side heats water in the upper section and the cold side cools water in the lower section, allowing for efficient energy transfer and circulation without external pumps or lines, using a Peltier element for compact and efficient heating and cooling within the tank.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the return flow temperature from the buffer tank is kept above 55°C to prevent bacterial growth, then drinking water hygiene is maintained, but heat source efficiency deteriorates due to higher temperature differences
Solution Approach 1:
The buffer tank is divided into three distinct zones: a hot water zone (above 55°C) for hygiene, a warm water zone (40-55°C) for heat storage, and a cold water zone (below 40°C) for cooling. This segmentation allows the system to maintain hygiene in the hot zone while storing energy at lower temperatures that are more efficient for heat sources.
Solution Approach 2:
A heat pump is introduced as an intermediary device between the cold and hot zones. The heat pump extracts heat from the cold water zone and transfers it to the hot water zone, enabling efficient energy transfer without requiring the entire buffer tank to be maintained at high temperatures for hygiene purposes.
2Device complexity
If the buffer tank uses a conventional single-zone design, then the structure is simple, but it cannot simultaneously achieve high heat source efficiency and drinking water hygiene requirements
Solution Approach 1:
The buffer tank is divided into three distinct zones: a hot water zone (above 55°C) for hygiene, a warm water zone (40-55°C) for heat storage, and a cold water zone (below 40°C) for cooling. This segmentation allows the system to maintain hygiene in the hot zone while storing energy at lower temperatures that are more efficient for heat sources.
Solution Approach 2:
A heat pump is introduced as an intermediary device between the cold and hot zones. The heat pump extracts heat from the cold water zone and transfers it to the hot water zone, enabling efficient energy transfer without requiring the entire buffer tank to be maintained at high temperatures for hygiene purposes.
3Ease of operation
If external pumps and heat exchange lines are used for heat transfer, then heating and cooling functions are achieved, but the system complexity and energy losses increase
Solution Approach 1:
The heat pump is integrated directly into the buffer tank structure, merging the heating and cooling functions with the storage function. This eliminates the need for external pumps and heat exchange lines, reducing system complexity and minimizing energy losses associated with external heat transfer components.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This configuration ensures high efficiency in reheating warm water (>95%) while maintaining hygiene standards by using internal energy within the buffer tank, eliminating the need for external heat sources and reducing energy losses, and allows for a simple, long-lasting heat pump design.
Implementation Method 1
a heat pump with a warm side for heating the water of the buffer storage and a cold side for cooling the water of the buffer storage
Implementation Method 2
using a Peltier element for compact and efficient heating and cooling within the tank
Data Source
Figure 1~2
AI summary
The present invention relates to a buffer tank for heating and/or drinking water heating systems for providing stored heat in the form of warm or warmer water, which stores warmer water in a first housing section and colder water in a second housing section and is provided with a heat pump. The heat pump has a hot side for heating the water in the buffer tank and a cold side for cooling the water in the buffer tank. A separating element is provided for separating the first housing section from the second housing section. With the help of such a buffer storage, relatively small heat sources, such as solar modules, can be used. The invention also relates to a heat supply system with a buffer storage. For a good efficiency of the heat source, it is essential that the return flow temperature of the medium flowing from the buffer tank to the heat source is as low as possible. In the case of a central drinking water supply, however, this requirement conflicts with drinking water hygiene. When it comes to drinking water hygiene, the hot water temperature in the distribution system must not fall below around 55°C. There is therefore a constant need to provide a heat supply system and a buffer storage tank which make it possible to use the efficiency of the heat sources used without any losses and to comply with the hygiene requirements of drinking water use. To solve this problem, the present invention proposes a buffer storage tank in which the heat pump is arranged in the separating element, with the warm side facing the first housing section and the cold side facing the second housing section.