Replaceable Heat Exchanger Layout for Scale-Prone Heat Pump Water Heaters
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Solution Overview
Problem
The accumulation of scale in the water-refrigerant heat exchanger of heat pump water heaters leads to increased maintenance costs due to the difficulty in replacing the heat exchanger, as it is often covered and housed in a hard case, making it hard to access and replace without replacing the entire unit.
Innovation Solution
A heat pump water heater design that includes a first and second water-refrigerant heat exchanger, where the first heat exchanger can be replaced independently without affecting the second, allowing for easy and low-cost maintenance by separating their installation and refrigerant paths, enabling the first heat exchanger to be replaced without replacing the entire unit.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If the water-refrigerant heat exchanger is covered by heat-insulating material and housed in a hard case, then thermal insulation performance is improved, but ease of repair deteriorates
Solution Approach 1:
The water-refrigerant heat exchanger is divided into a first heat exchanger and a second heat exchanger that can be replaced independently. The first heat exchanger is positioned to be accessible from the outside without removing the heat-insulating material or disassembling the hard case, while the second heat exchanger remains protected. This segmentation allows maintenance personnel to replace the first heat exchanger easily while maintaining thermal insulation for the overall system.
2Strength
If the water-refrigerant heat exchanger is housed in a hard case with fan above it, then structural protection is improved, but ease of operation deteriorates
Solution Approach 1:
The first water-refrigerant heat exchanger is extracted from the enclosed hard case structure and positioned in an accessible location where it can be removed without disassembling the hard case or removing the fan. The second heat exchanger remains within the protected enclosure. This extraction allows easy maintenance of the first heat exchanger while maintaining the protective structure for the second heat exchanger.
3Reliability
If scale accumulates in the water-refrigerant heat exchanger, then heat exchange efficiency deteriorates, but replacement cost increases
Solution Approach 1:
The system uses two separate heat exchangers with different functional qualities: the first heat exchanger is designed for easy replacement and serves as the primary heating element subject to scale accumulation, while the second heat exchanger is protected and serves as a backup or secondary element. When scale reduces the efficiency of the first heat exchanger, it can be replaced independently at low cost without affecting the second heat exchanger, thus maintaining overall system reliability while minimizing maintenance costs.
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 design allows for the easy replacement of the first water-refrigerant heat exchanger, reducing maintenance costs and minimizing downtime, while maintaining the functionality of the second heat exchanger, thus addressing the issue of scale accumulation and flow path narrowing.
Implementation Method 1
a compressor configured to compress a refrigerant
Implementation Method 2
a first water-refrigerant heat exchanger configured to exchange heat between the refrigerant and water; a second water-refrigerant heat exchanger configured to exchange heat between the refrigerant and water
Data Source
Figure 1
Figure 2
Figure 3~4
AI summary
A heat pump water heater includes: a compressor; a first water-refrigerant heat exchanger; a second water-refrigerant heat exchanger; refrigerant paths capable of forming a refrigerant circuit; and water channels including a flow channel, the flow channel leading hot water that has passed through the second water-refrigerant heat exchanger to the first water-refrigerant heat exchanger. The heat pump water heater is able to perform a heating operation. In the heating operation, the hot water heated in the second water-refrigerant heat exchanger is fed to the first water-refrigerant heat exchanger and the hot water further heated in the first water-refrigerant heat exchanger is supplied to a downstream side of the water channels. The first water-refrigerant heat exchanger is able to be replaced without replacing the second water-refrigerant heat exchanger.