Absorption Heat Pump Refrigerant Bleed for High-Temperature Heating
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Solution Overview
Problem
Conventional heat pumps face efficiency drops when trying to achieve water temperatures higher than 65°C, especially in low external temperatures or for domestic hot water needs, due to limitations in refrigerant flow and heat exchanger performance.
Innovation Solution
The heat pump system increases the ammonia concentration in the rich solution by bleeding off refrigerant from the condenser and mixing it with the solution entering the generator, using a liquid-liquid injector, which allows for higher temperatures while reducing the load on the desorber and rectifier by introducing refrigerant at a strategic point in the circuit, minimizing power costs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If the heat pump operates to provide high temperature water (higher than 65°C), then the heating system can replace traditional boilers and provide high temperature heating, but the heat pump efficiency falls off drastically
Solution Approach 1:
The patent changes the concentration parameter of the refrigerant solution by bleeding off refrigerant from the condenser and mixing it with the rich solution entering the generator. This parameter change allows the system to maintain high efficiency while delivering high temperature water (higher than 65°C) by optimizing the ammonia concentration in the rich solution, thereby resolving the efficiency drop that normally occurs at high temperatures.
2Temperature
If the heat pump increases water temperature for domestic hot water or low external temperature conditions, then the system meets heating demands, but the effective efficiency becomes considerably different from theoretical efficiency
Solution Approach 1:
The patent stabilizes efficiency across varying operating conditions by dynamically adjusting the refrigerant concentration through the bleeding and mixing system. This allows the heat pump to maintain reliable and stable efficiency whether operating for domestic hot water, low external temperatures, or high temperature heating requirements.
3Temperature
If the heat pump delivers high temperature water to fixed heating systems, then traditional boiler systems can be replaced without modification, but the system requires burner power modulation which decreases pump power
Solution Approach 1:
The patent changes the refrigerant concentration parameter to enable high temperature water delivery while maintaining constant pump power. By bleeding refrigerant from the condenser and mixing it with the rich solution, the system achieves high temperature output (higher than 65°C) without the need to modulate or decrease pump power, thus avoiding the unacceptable power reduction in traditional solutions.
4Power
If the heat pump operates at maximum power to maintain high efficiency, then energy conversion is optimized, but the system cannot achieve high water temperatures due to refrigerant flow limitations
Solution Approach 1:
The patent resolves the power-temperature tradeoff by changing the refrigerant concentration parameter. The system operates the generator at maximum power for optimal efficiency while the bleeding and mixing system adjusts the ammonia concentration in the rich solution to enable high water temperature output. This parameter change removes the refrigerant flow limitation that previously prevented high temperature delivery at maximum power.
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 maintains high efficiency and maximum power output, extending the system's working conditions and improving performance at high water temperature requirements, especially in extreme conditions, by optimizing the heat exchanger loads and refrigerant flow.
Implementation Method 1
an evaporator outlet 7B connected by a third line 8 to a first inlet 10B for vapour from said first fluid into the absorber
Implementation Method 2
a heat pump operating with a cycle using as refrigerant a first fluid (in this specific case ammonia), which is absorbed in a second fluid (in this case water)
Implementation Method 3
a conventional generator 2 or desorber presenting a finned gas burner 35
Implementation Method 4
a conventional generator 2 or desorber presenting a finned gas burner 35, which feeds a conventional plate column 36
Implementation Method 5
a condenser 4 of conventional type, positioned in heat exchange contact with a transmission fluid which feeds the heating plant
Implementation Method 6
A countercurrent heat exchanger 34 is provided downstream of the condenser 4 in a second line 6
Data Source
Figure 1
AI summary
An absorption heat pump with a system for improving its efficiency under extreme conditions by bleeding off refrigerant downstream of the condenser and mixing it with the rich solution after this latter has been at least partially heated by the absorber and before it is fed into the desorber.