Cascade phase change material (PCM) heat pump water heater
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Solution Overview
Problem
Conventional heat pump systems for water heating are inefficient in utilizing phase change materials (PCMs) and natural refrigerants, particularly in managing thermal energy storage and distribution effectively across multiple heat pumps and heat exchangers.
Innovation Solution
A cascade phase change material (PCM) natural refrigerant heat pump system is designed with multiple heat pumps connected in parallel or series, a thermal battery bank of PCM cells, and a circulator pump, forming a closed loop with a heat exchanger, allowing for efficient charging, discharging, and load meeting modes through controlled circulation and temperature management.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If conventional heat pump systems use traditional refrigerants and direct water heating, then the system structure is simple, but the energy efficiency and thermal energy storage capability are insufficient
Solution Approach 1:
The system divides the thermal battery into multiple PCM cells with different phase change temperatures, creating a segmented thermal storage architecture. Each cell handles specific temperature ranges, improving overall energy efficiency while maintaining manageable system complexity through modular design
Solution Approach 2:
The patent implements a nested structure where heat exchangers are placed inside PCM cells, which are arranged in series within the thermal battery. This nested arrangement maximizes thermal energy storage density and efficiency without proportionally increasing system complexity
2Productivity
If multiple heat pumps are used in parallel, then the thermal energy storage and distribution efficiency is improved, but the system complexity increases
Solution Approach 1:
Each heat pump in the parallel configuration serves multiple functions: heating water during operation, charging the thermal battery, and potentially providing backup capacity. This multi-functionality justifies the increased complexity by maximizing productivity and thermal energy management efficiency
Solution Approach 2:
The system performs preliminary charging of the thermal battery during off-peak hours or when excess capacity is available, preparing thermal energy in advance for later distribution. This preliminary action optimizes productivity by decoupling energy generation from immediate demand, justifying the parallel heat pump configuration
3Ease of operation
If a closed loop system with circulator pump is used, then the controlled circulation and temperature management are improved, but the device complexity increases
Solution Approach 1:
The circulator pump system incorporates temperature sensors and control logic that monitor thermal battery charge state and water temperature, automatically adjusting circulation rates. This feedback mechanism simplifies operation by providing automatic temperature management, justifying the added complexity of the closed loop system
Solution Approach 2:
The system uses temperature differential control where the circulator pump automatically responds to temperature differences between the heat pumps and thermal battery, maintaining optimal circulation without external intervention. This self-service capability improves ease of operation while the modular closed loop design keeps complexity manageable
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 enhances the coefficient of performance (COP) by optimizing thermal energy storage and distribution, ensuring efficient water heating while maintaining safe operating temperatures and maximizing flow rates, thus improving the overall efficiency and effectiveness of the water heating system.
Implementation Method 1
Cascade phase change material (PCM) heat pump water heater
Implementation Method 2
A thermal battery bank including multiple PCM battery cells is connected to the heat exchanger
Implementation Method 3
A heat exchanger is connected to the multiple heat pumps
Implementation Method 4
a refrigerant, such as R-410A, R-32. This refrigerant then cycles through a heat exchanger where it can heat the load side water
Implementation Method 5
A circulator pump is connected to the heat exchanger and the multiple PCM battery cells
Data Source
AI summary
One embodiment provides a cascade phase change material (PCM) natural refrigerant heat pump system that includes multiple heat pumps. A heat exchanger is connected to the multiple heat pumps. A thermal battery bank including multiple PCM battery cells is connected to the heat exchanger in a closed loop. A circulator pump is connected to the heat exchanger and the multiple PCM battery cells.