Heat Pump Bypass Cooling for Stable Turbocompressor Partial Load
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Solution Overview
Problem
Heat pumps using turbocompressors face limitations in partial load operation due to potential flow collapse and thermal stress issues, especially when dealing with fluctuating heat source performance, limiting their efficiency and operational range.
Innovation Solution
The method involves diverting a liquid partial flow via a second bypass line to mix with the first partial flow before compression, adjusting the ratio of bypass flows to maintain saturated vaporization and prevent thermal decomposition, and using adjustable valves and pumps to control the volume flow, ensuring a minimum volume flow and avoiding material damage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If the speed of turbo compressor is reduced to adapt to reduced volume flow, then the heat pump can operate at lower heat source performance, but flow collapse and pumping process occur limiting operation to max 90% load range
Solution Approach 1:
The fluid flow through the turbo compressor is segmented into two separate flows: a first partial flow (70-90% of total) that passes through the compressor, and a second partial flow (10-30% of total) that bypasses the compressor through a bypass line. This segmentation allows the compressor to operate within its stable flow range while still achieving lower overall system load operation.
Solution Approach 2:
A bypass line with bypass valve acts as an intermediary pathway, allowing a portion of the fluid to circumvent the compressor. This mediator enables the system to achieve partial load operation without forcing the compressor into its unstable low-flow region, thus maintaining reliability while extending adaptability.
2Adaptability or versatility
If bypass valve is used to throttle volume flow through compressor, then partial load operation is enabled, but suction gas and compressed gas temperatures increase causing thermal stress
Solution Approach 1:
The second partial flow that bypasses the compressor is used to evaporate liquid refrigerant in the evaporator. This phase transition from liquid to vapor absorbs heat, and the resulting cold vapor mixes with the compressed gas from the compressor, reducing the overall temperature of the compressed gas and preventing thermal stress.
Solution Approach 2:
The system changes the temperature parameter of the compressed gas by introducing cold vapor from the evaporator. This parameter change occurs through mixing the hot compressed gas with the cold evaporated vapor, thereby reducing the temperature to safe operating levels while maintaining partial load operation capability.
3Adaptability or versatility
If more fluid is diverted through bypass line to extend partial load range, then lower heat source performance is accommodated, but compressed gas temperature increases risking fluid decomposition and material damage
Solution Approach 1:
The second partial flow bypassing the compressor undergoes phase transition by evaporating liquid refrigerant in the evaporator. This evaporative cooling process produces cold vapor that mixes with the compressed gas, actively cooling it and preventing thermal decomposition and material damage even when large bypass flows are used to achieve low partial load operation.
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 extends the partial load range of heat pumps with turbo compressors, preventing fluid and material damage by maintaining optimal temperature and volume flow, making them suitable for fluctuating heat sources and high-temperature fluids.
Implementation Method 1
the liquid partial flow is branched off from the fluid circuit after partial liquefaction and upstream of the evaporator via a second bypass line and mixed with the first partial flow before compression
Implementation Method 2
By adding the liquid phase, the temperature of the first partial flow is lowered from the compressed gas temperature to a lower mixing temperature
Implementation Method 3
the fluid is at least partially evaporated and subsequently compressed
Implementation Method 4
the fluid is then at least partially liquefied to deliver thermal energy to a heat sink at a higher temperature level than the heat source
Implementation Method 5
the fluid is then expanded to cool
Data Source
Figure 1~2
Figure 3~4
Figure 5
AI summary
The invention relates to a heat pump (12, 26) with a fluid circuit (21, 28) with at least one evaporator (10), a downstream compressor unit (7), at least one downstream liquefier (8), and a downstream expansion unit (9), and a first bypass line (42) with at least one bypass valve (43), so that the fluid circuit can be fluidically connected, downstream of the compressor unit (7) and upstream of the liquefier (8), to the fluid circuit downstream of the evaporator (10) and upstream of the compressor unit (7). The heat pump has a region of the part-load operation that is broadened in the direction of low heat source power. To that end, the heat pump comprises a second bypass line (45) with means for metering the throughflow quantity (46), wherein by means of the second bypass line a liquid phase of the fluid can be introduced into the first bypass line (42).