Optimized management method of an environmentally friendly heat pump
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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, reducing efficiency and reliability.
Innovation Solution
A management logic for heat pumps that regulates the wet fraction of the refrigerant at the compressor inlet by adjusting the evaporative power of the evaporator, ensuring the temperature difference between the lubricating oil and the refrigerant remains above a safety threshold to prevent condensation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If low environmental impact refrigerants (low GWP) are used, then environmental friendliness is improved, but compressor delivery temperature increases causing overheating and lubrication issues
Solution Approach 1:
The patent applies parameter changes by dynamically adjusting the evaporative power of the evaporator (changing its thermal performance parameter) to control the refrigerant state at compressor inlet. This regulation modifies the compression process parameters to achieve optimal delivery temperature that prevents overheating while maintaining the use of low GWP refrigerants.
Solution Approach 2:
The patent implements feedback control through a management logic that continuously monitors the temperature difference between lubricating oil and refrigerant, and adjusts the evaporator's evaporative power accordingly. This closed-loop feedback ensures the temperature difference remains above the safety threshold, preventing refrigerant condensation in the oil while optimizing compressor delivery temperature.
2Reliability
If compressor delivery temperature is reduced to prevent overheating, then reliability is improved, but the temperature difference between lubricating oil and refrigerant decreases risking condensation
Solution Approach 1:
The patent uses feedback control to continuously monitor the temperature difference between lubricating oil and refrigerant, and dynamically adjusts the evaporator's evaporative power to maintain this difference above a safety threshold. This prevents refrigerant condensation in the oil while optimizing compressor delivery temperature for reliability.
Solution Approach 2:
The patent changes the evaporative power parameter of the evaporator to regulate the refrigerant state entering the compressor. By adjusting this parameter, the system optimizes the compression process to achieve delivery temperatures that ensure reliability without causing the temperature difference to drop below the condensation threshold.
3Temperature
If evaporative power of evaporator is increased to regulate wet fraction, then compressor delivery temperature is optimized, but system complexity increases
Solution Approach 1:
The patent implements a feedback control system that uses temperature difference measurements to automatically adjust the evaporator's evaporative power. This feedback mechanism simplifies the control approach by using a single measurable parameter (temperature difference) to regulate the system, avoiding the need for complex multi-parameter control while achieving optimal compressor delivery temperature.
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 optimal compressor delivery temperatures, ensuring high performance and reliability of the heat pump while preventing refrigerant condensation in the lubricating oil.
Implementation Method 1
at least one first heat exchanger in which the operating fluid absorbs, at constant pressure, heat energy from a first fluid F.f
Implementation Method 2
a compressor driven by a motor and designed to compress said operating fluid between a minimum pressure thereof, that it has at the outlet of the first exchanger, to the maximum pressure that it has at the inlet of the second exchanger
Implementation Method 3
at least a second heat exchanger, in which the same operating fluid yields, at constant pressure, part of the heat energy thereof to a second fluid F.c
Implementation Method 4
a lamination valve that achieves an expansion, at a substantially constant enthalpy, and a cooling of the operating fluid
Data Source
Figure 1~2
Figure 3
Figure 4(a)~4(c)
AI summary
The object of the present invention is a method for the management and control of a thermodynamic machine (HP) based on a compression/expansion cycle of an operating fluid and comprising at least: a first heat exchanger (11; 12) in which said operating fluid absorbs thermal energy at constant pressure t from a cold well; a second heat exchanger (12; 11) in which said operating fluid yields part of the thermal energy thereof to a hot well, at constant pressure; an expansion valve (14) adapted to carry out constant enthalpy expansion and cooling of said operating fluid; a compressor (13; C) adapted to compress said operating fluid, 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 for detecting 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 difference in temperature between said lubricating oil in the compressor (13; C) and said operating fluid at the delivery of the compressor (13; C) is kept equal to or higher than a safety threshold OIL_SH such that there is no condensation of said operating fluid in said lubricating oil. The delivery temperature Tm of said compressor (13; C) is regulated as long as it does not substantially approximate and/or reach an optimised target delivery temperature Tm_target_opt that is a function of at least the rotation frequency of said compressor (13; C).