Method for managing a heat pump operating with a low environmental impact operating fluid
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Heat pumps using low environmental impact refrigerants face challenges in maintaining optimal compressor delivery temperatures, which can lead to overheating and lubrication issues, compromising compressor reliability and reducing the operating range.
Innovation Solution
A management logic for heat pumps that regulates the wet fraction of the refrigerant at the compressor inlet by adjusting the evaporator's power, using temperature sensors and a PID control system to maintain a safe temperature difference between the lubricating oil and the refrigerant, preventing condensation and ensuring optimal performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If low GWP refrigerants are used, then environmental impact is reduced, but compressor delivery temperature increases causing overheating and lubrication issues
Solution Approach 1:
The system dynamically adjusts operating parameters including evaporator power, expansion valve opening, and compressor speed to control the refrigerant state at compressor inlet, thereby managing delivery temperature within safe operating limits while using low GWP refrigerants
Solution Approach 2:
Temperature sensors monitor the temperature difference between lubricating oil and refrigerant, feeding this information to a PID control system that continuously adjusts the expansion valve and evaporator power to maintain optimal delivery temperature and prevent overheating
2Object-affected harmful factors
If low GWP refrigerants are used, then environmental impact is reduced, but compressor reliability deteriorates due to overheating and lubrication issues
Solution Approach 1:
The PID control system continuously monitors temperature difference between lubricating oil and refrigerant, adjusting expansion valve position and evaporator power in real-time to prevent delivery temperature from exceeding safe limits, thereby protecting compressor reliability
Solution Approach 2:
The system proactively controls the refrigerant state at compressor inlet by pre-adjusting expansion valve opening and evaporator power before excessive temperature rise occurs, preventing overheating and lubrication breakdown before they can compromise compressor reliability
3Reliability
If evaporator power is increased to control delivery temperature, then compressor reliability is maintained, but heat pump performance and operating range are reduced
Solution Approach 1:
The system dynamically adjusts evaporator power and expansion valve opening based on real-time operating conditions and refrigerant state, optimizing the balance between delivery temperature control and heat pump performance across varying load conditions
Solution Approach 2:
The system applies partial cooling control by adjusting evaporator power to the minimum necessary level to maintain safe delivery temperature, avoiding excessive reduction in heat pump performance while still protecting compressor reliability
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 the compressor's reliability and performance while using low GWP refrigerants, avoiding overheating and lubrication issues, and maintains the operating range of the heat pump.
Implementation Method 1
regulates the wet fraction of the refrigerant at the compressor inlet by adjusting the evaporator's power
Implementation Method 2
at least a first heat exchanger in which the operating fluid absorbs, at constant pressure, heat energy from a first fluid F.f
Implementation Method 3
at least a second heat exchanger, in which the same operating fluid yields, at constant pressure, part of its heat energy to a second fluid F.c
Implementation Method 4
a lamination valve that achieves an expansion, at substantially constant enthalpy, and a cooling of the operating fluid
Implementation Method 5
a compressor actuated by a motor and designed to compress said operating fluid between a minimum pressure thereof... to the maximum pressure that it has at the inlet of the second exchanger
Data Source
Figure 1~2
Figure 3
Figure 4(a)~4(c)
AI summary
The present invention relates to a method for managing and controlling a heat pump (HP) based on a compression/expansion thermodynamic cycle of an operating fluid and comprising at least: a first heat exchanger (11; 12) in which said operating fluid absorbs heat energy at constant pressure from a cold well; a second heat exchanger (12; 11) in which said operating fluid yields part of its heat energy at constant pressure to a hot well; an expansion valve (14) placed between said first (11; 12) and second (12; 11) heat exchanger adapted to carry out a constant enthalpy expansion and cooling of said operating fluid; a compressor (13; C) adapted to compress said operating fluid between a minimum pressure thereof that it has at the outlet of said first heat exchanger (11; 12) and a maximum pressure thereof that it has at the inlet of said second heat exchanger (12; 11), said compressor (13; C) being able to suck and compress a wet operating fluid with a suitable percentage of liquid fraction, a plurality of temperature sensors being able to detect at least the delivery temperatures Tm of said compressor, of an evaporation temperature SST in said first exchanger (11; 12), of a condensation temperature SDT in said second exchanger (12; 11). The temperature difference between said lubricating oil in the compressor (13; C) and said operating fluid at the compressor delivery (13; C) is kept equal to or greater than a safety threshold OIL_SH such that there is no condensation of said operating fluid in said lubricating oil.