CO2 Heat Pump with Stratified Thermal Storage
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Solution Overview
Problem
Conventional heating and cooling systems using synthetic refrigerants face obsolescence due to environmental regulations and are inefficient in low-temperature conditions, requiring alternative solutions that can operate effectively with natural refrigerants like CO2 and adapt to varying water temperatures.
Innovation Solution
A heating and cooling system utilizing a stratified thermal storage tank (STST) with a transcritical heat pump that includes an evaporator and gas cooler, operating in a transcritical cycle, to manage temperature differentials and prevent ice formation, employing CO2 as the refrigerant.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional heat pumps use synthetic refrigerants to achieve adequate heating and cooling performance, then heating and cooling efficiency is maintained, but environmental compliance deteriorates due to greenhouse gas emissions and upcoming bans
Solution Approach 1:
The patent transitions from synthetic refrigerants to natural refrigerants (CO2), changing the chemical composition parameter while maintaining heat transfer functionality. This substitution eliminates harmful emissions while preserving heating and cooling performance through optimized system design including transcritical cycle operation and thermal storage integration
2Use of energy by moving object
If conventional heat pumps operate with water sources at temperatures near freezing to utilize available thermal energy, then energy efficiency is improved, but system reliability deteriorates due to ice formation and shutdown requirements
Solution Approach 1:
The system performs preliminary heating of water from the thermal source before it enters the evaporator by passing it through the gas cooler first. This pre-heating action raises the water temperature above freezing point, preventing ice formation in the evaporator and enabling continuous operation during winter months while maintaining energy efficiency by utilizing the low-temperature thermal source
Solution Approach 2:
The patent introduces a thermal storage tank as an intermediary component between the water source and the heat pump system. This intermediary allows the system to decouple the low-temperature water source from the evaporator, enabling the water to be pre-heated and stored at temperatures that prevent freezing while still extracting useful thermal energy
3Reliability
If conventional heat pumps are shut down in winter to prevent ice formation, then system reliability is maintained, but productivity deteriorates due to loss of heating capability and requirement for alternative energy sources
Solution Approach 1:
The thermal storage tank serves as an intermediary that enables continuous operation by storing pre-heated water at temperatures above freezing. This intermediary component allows the evaporator to operate continuously without ice formation while maintaining heating productivity, as the stored thermal energy buffers against freezing conditions
4Duration of action of stationary object
If conventional heat pumps require alternative energy sources during winter to maintain operation, then continuous heating is achieved, but device complexity increases due to multiple energy source integration
Solution Approach 1:
The thermal storage tank provides multi-functionality by serving as both a heat source during cooling mode and a pre-heating device during heating mode. This universal component enables continuous operation throughout the year using a single integrated system design, eliminating the need for separate alternative energy sources and reducing overall system complexity
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
Enhances the efficiency of heating and cooling systems by utilizing CO2 heat pumps, allowing operation during winter and reducing ice formation risks, while complying with environmental regulations.
Implementation Method 1
a stratified thermal storage tank (STST) having an interior region extending between a first end and a second end, where the interior region includes a hot section at or proximate to the first end, a cold section at or proximate to the second end, and a thermocline section in between the hot and cold sections
Implementation Method 2
a first heat pump including a first evaporator and a gas cooler... so that first heat transported from the STST by the third amount of the fluid to the first evaporator is communicated by way of the first heat pump to the gas cooler and then transported from the gas cooler by the second amount of fluid to the hot section of the STST
Implementation Method 3
operating in a transcritical cycle, to manage temperature differentials and prevent ice formation, employing CO2 as the refrigerant
Data Source
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AI summary
Heating and/or cooling systems, related methods, particularly those utilized for the heating and/or cooling of large structures, areas, or environments are disclosed herein. In one example embodiment, such a system includes a stratified thermal storage tank (STST), heat exchanger, and heat pump. A first amount of a fluid can flow from the STST to a heating load and then to the heat exchanger, at which residual heat can be received, and which is configured to receive a medium from an external source. The medium can flow from the source through the heat exchanger to an evaporator of the heat pump and transport first heat to the evaporator, including the residual heat. A risk of ice formation at the evaporator is reduced/eliminated. The heat pump is configured to cycle a refrigerant, so that the first heat is transferred from the evaporator to a gas cooler, and then to the STST.