Improvements to thermodynamic solar heat transfer systems
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Solution Overview
Problem
Thermodynamic solar systems used in cooler climates face efficiency losses and safety hazards due to frosting and icing on heat transfer panels, which impede heat transfer and pose a risk of ice accumulation.
Innovation Solution
Incorporation of temperature and humidity sensors to initiate a hot gas defrost cycle only when conditions are conducive to frost or ice formation, combined with thicker panel walls to handle higher pressures and the use of R-134a refrigerant for increased efficiency and safety, and a single water tank with a secondary heat exchange coil to reduce Legionella risks and system complexity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If liquid refrigerant at -20°C is used in cooler climates, then heat transfer efficiency is improved, but frosting and icing on panels occurs
Solution Approach 1:
The patent converts the harmful cold refrigerant temperature that causes frosting into a beneficial defrosting mechanism by reversing the refrigerant flow direction. The cold refrigerant that would normally cause ice formation is instead used to melt accumulated frost and ice on the panels, transforming the harmful effect into a self-cleaning mechanism.
Solution Approach 2:
The system implements periodic reversal of refrigerant flow direction through control means that respond to temperature and humidity sensor readings. This periodic action allows the system to alternate between normal heat transfer mode and defrosting mode, maintaining efficiency while preventing harmful ice accumulation.
2Productivity
If ice builds up on panels, then heat transfer is impeded, but safety hazards arise from ice slipping
Solution Approach 1:
The system uses the cold refrigerant that would normally contribute to ice accumulation as a controlled defrosting agent. By reversing flow direction, the cold refrigerant selectively melts ice in critical areas, eliminating safety hazards while preserving heat transfer efficiency.
Solution Approach 2:
Temperature and humidity sensors provide continuous feedback about environmental conditions and panel surface state. The control means processes this feedback to determine when defrosting is necessary, activating refrigerant flow reversal only when ice accumulation reaches levels that would impede heat transfer or create safety hazards.
3Object-affected harmful factors
If hot gas defrost cycle is initiated, then frost and ice are prevented, but system complexity increases
Solution Approach 1:
The system performs self-diagnosis and self-defrosting using existing components. Temperature and humidity sensors monitor conditions, and the control means automatically reverses refrigerant flow when needed, eliminating the need for separate heating elements, motors, or complex mechanical defrosting mechanisms.
Solution Approach 2:
The refrigerant flow reversal mechanism serves dual purposes: it enables defrosting of panels while simultaneously maintaining system efficiency. The same control system that manages normal refrigerant circulation also handles defrosting operations, consolidating functions rather than adding separate systems.
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
The system maintains efficiency while preventing frost and ice buildup, ensuring safety and reducing the risk of Legionella bacteria, with improved heat transfer and reduced system complexity and costs.
Implementation Method 1
one or both of a temperature sensor (70) and/or a humidity sensor (80) for measuring ambient temperature and/or humidity conditions
Implementation Method 2
one or both of a temperature sensor (70) and/or a humidity sensor (80) for measuring ambient temperature and/or humidity conditions
Implementation Method 3
the flow of refrigerant, is reversed to divert hot refrigerant vapour from the heat pump (2) back into the panel (1, 1a) when the ambient conditions measured by the temperature sensor (70) and/or humidity sensor (80) are cold enough or include sufficient air moisture for frost to form on the panel
Implementation Method 4
the flow of refrigerant, is reversed to divert hot refrigerant vapour from the heat pump (2) back into the panel (1, 1a) when the ambient conditions measured by the temperature sensor (70) and/or humidity sensor (80) are cold enough or include sufficient air moisture for frost to form on the panel
Implementation Method 5
A refrigerant fluid, R407c, (3) is entered to the panel as a liquid at -20°C. The panel is outside, and absorbs heat from ambient conditions (8), including the sun during daytime, which converts the liquid into a vapour
Implementation Method 6
The panel is outside, and absorbs heat from ambient conditions (8), including the sun during daytime, which converts the liquid into a vapour
Implementation Method 7
This vapour then passes into the heat pump (2), where it is compressed, raising the temperature of the vapour to approximately 80°C
Implementation Method 8
This hot vapour (hot refrigerant vapour) is entered into a heat exchanger or condenser (10, 20), where the hot refrigerant vapour imparts its heat into water (5, 5a, 5b)
Data Source
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AI summary
The invention describes improvements to heat transfer systems applied to buildings, particularly those commonly referred to as Thermodynamic or Solar Thermodynamic.