Hot Water Tank Stratification for Heat Pump Efficiency
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Solution Overview
Problem
The existing heating and hot water supply systems face inefficiencies due to the need to heat the entire tank to high temperatures for applications like dishwashers, which reduces the operation efficiency of heat pumps and increases energy consumption and heat dissipation losses.
Innovation Solution
A system with a hot water storage tank, liquid and water heaters, heat exchangers, pumps, and valve configurations that allow for temperature stratification, enabling medium-temperature and high-temperature water to be stored separately within the tank, reducing the need to heat the entire tank to high temperatures.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the entire tank is heated to high temperature (55°C) to meet dishwasher requirements, then the dishwasher can function properly, but the heat pump operation efficiency decreases and energy consumption increases
Solution Approach 1:
The hot water storage tank is divided into multiple temperature zones (upper, middle, lower parts) that can be independently controlled. The system segments the heating process by targeting specific zones rather than heating the entire tank, allowing high-temperature water to be generated locally for dishwasher use while maintaining lower temperatures in other zones to preserve heat pump efficiency.
Solution Approach 2:
Different parts of the tank are maintained at different temperatures according to local needs. The upper part of the tank is heated to high temperature (55°C) specifically for dishwasher supply, while the middle and lower parts remain at lower temperatures (40-45°C) for shower and kitchen use, optimizing overall energy efficiency.
2Temperature
If the entire tank is heated to high temperature (55°C), then high-temperature hot water is available for dishwasher, but heat dissipation loss increases
Solution Approach 1:
The tank is segmented into temperature zones with only the necessary volume heated to high temperature. By heating only the upper part of the tank to 55°C rather than the entire tank, the surface area exposed to heat dissipation is reduced, minimizing energy loss while still providing sufficient high-temperature hot water for dishwasher operations.
3Temperature
If the entire tank is heated to high temperature, then high-temperature hot water supply is ensured, but the system efficiency deteriorates
Solution Approach 1:
Instead of heating the entire tank to the maximum required temperature, the system applies partial action by heating only the necessary portion (upper part of the tank) to high temperature. The middle and lower parts are heated to lower temperatures sufficient for their respective applications, avoiding excessive energy input while meeting all hot water supply requirements.
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 approach reduces energy consumption by optimizing the temperature of the hot water storage tank, improving the efficiency of the heat pump operation and minimizing heat dissipation losses, while ensuring high-temperature water is available when needed.
Implementation Method 1
a liquid-water heat exchanger (5) configured to exchange heat between the liquid and water
Implementation Method 2
The heated water diffuses to a tank upper part by buoyancy generated by a density difference
Data Source
AI summary
A hot water supply system that can reduce energy consumption is provided. The hot water supply system includes a liquid heater for heating a liquid, a liquid-water heat exchanger, a water-heating circuit in which the liquid is circulated between the liquid heater and the liquid-water heat exchanger, a lower outward path for leading water from a lower part of a hot water storage tank to the liquid-water heat exchanger, the upper return path for leading the water from the liquid-water heat exchanger to an upper part of the hot water storage tank, a middle outward path for leading the water from a middle part of the hot water storage tank to the liquid-water heat exchanger, a middle return path for leading the water from the liquid-water heat exchanger to a middle part of the hot water storage tank.