Heat pump water heating system
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Solution Overview
Problem
In water heating systems using R410A as the refrigerant, scale deposition occurs at the highest hot water storage temperature, reducing heat exchange efficiency and increasing the time required to reach this temperature, leading to increased scale formation.
Innovation Solution
A heat pump water heating system with multiple circulation circuits and a controller that switches between a heat pump and a boiler as the heat source based on tank water temperature, using the higher-temperature boiler source when the tank water reaches a preset temperature to reduce boiling time and scale deposition.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If the heat pump is used to heat water to the highest storage temperature, then energy efficiency is improved, but scale deposition increases due to prolonged exposure at high temperature
Solution Approach 1:
The heating process is segmented into two distinct phases: a first heating phase using the heat pump to raise water temperature to a preset level, and a second heating phase using a boiler to reach the highest storage temperature. This segmentation allows each device to operate in its optimal temperature range, reducing scale deposition while maintaining energy efficiency.
Solution Approach 2:
The system changes the operating temperature parameter by switching between two heat sources. The heat pump operates at lower temperatures (below the preset temperature) where it is most efficient, while the boiler handles the high-temperature portion (above preset temperature) where scale deposition is minimized.
2Device complexity
If the heat pump operates continuously to reach highest storage temperature, then system simplicity is maintained, but boiling time increases leading to more scale formation
Solution Approach 1:
The heating process is divided into two phases with different heat sources. The first circulation pump operates the heat pump until preset temperature is reached, then the second circulation pump operates the boiler to complete heating to highest storage temperature, reducing total boiling time and scale formation.
3Loss of energy
If the heat pump heats water to highest storage temperature, then heat exchange efficiency decreases at high temperature, but adding a boiler increases system complexity
Solution Approach 1:
The heating function is segmented between two devices: the heat pump handles low-temperature heating efficiently, while the boiler handles high-temperature heating. This avoids the heat exchange efficiency loss that occurs when the heat pump operates at temperatures above its optimal range.
Solution Approach 2:
The water heating system achieves multi-functionality by combining a heat pump and a boiler, allowing it to operate efficiently across a wide temperature range. The controller manages both devices to provide optimal performance for different heating 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 scale deposition in the heat exchanger by shortening the time at high temperatures where scale formation occurs, improving heat exchange efficiency and reducing the amount of scale formed.
Implementation Method 1
a water-refrigerant heat exchanger that performs heat exchange between refrigerant and tank water by using a heat pump as a heat source
Implementation Method 2
a second circulation circuit including a second heat source having a higher temperature than the first heat source
Implementation Method 3
a third circulation circuit including a mixing tank that connects the first circulation circuit and the second circulation circuit
Data Source
AI summary
A controller of a heat pump water heating system drives circulation pumps, and uses a heat pump unit to increase a temperature of tank water within a hot water storage tank via a plate heat exchanger if the temperature of the tank water detected from a temperature sensor is lower than a heat source switch tank temperature, and the controller stops one of the circulation pump, drives other circulation pumps, and uses a boiler to increase the temperature of the tank water within the hot water storage tank via the plate heat exchanger in a shorter time than that of a case in which the heat pump unit is used to increase the temperature if the temperature of the tank water detected from the temperature sensor is equal to or higher than the heat source switch tank temperature.