Low capacity, low-GWP, HVAC system
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Current small capacity HVAC systems face challenges in using low global warming potential (GWP) refrigerants like R1233zd due to its low pressure nature, which affects system efficiency and packaging, and existing solutions like R410A have limitations in terms of GWP and cycle efficiency.
Innovation Solution
A vapor compression loop system utilizing a centrifugal compressor with a low or medium-pressure refrigerant, such as R1233zd, and refrigerant-lubricated bearings, along with a multi-loop configuration to mitigate pressure drops and enhance efficiency, including a high-speed impeller and inter-loop heat exchangers for heat transfer.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If low-GWP refrigerant R1233zd is used, then environmental impact is reduced and cycle efficiency is improved, but system packaging becomes difficult due to low pressure
Solution Approach 1:
The patent changes the operating pressure parameters by using a booster compressor to elevate the low suction pressure of R1233zd to a higher level, enabling the system to achieve both low GWP and practical packaging by modifying the pressure state of the refrigerant throughout the cycle
2Object-affected harmful factors
If low-pressure refrigerant R1233zd is used, then environmental impact is reduced, but compressor suction pressure becomes too low for practical operation
Solution Approach 1:
The booster compressor acts as an intermediary device between the evaporator and the main compressor, elevating the low-pressure refrigerant to a suitable suction pressure level, thus mediating the pressure mismatch and enabling practical operation of low-GWP refrigerants
3Volume of moving object
If high-speed centrifugal compressor is used, then system compactness is improved, but bearing lubrication becomes challenging with low-viscosity refrigerants
Solution Approach 1:
The patent replaces traditional oil-based mechanical lubrication with a refrigerant-based lubrication system, where the low-viscosity refrigerant itself serves as the lubricant, eliminating the need for separate lubrication mechanisms and enabling compact high-speed compressor design
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 achieves higher efficiency and compactness by using R1233zd, reducing GWP, and addressing the low-pressure limitations of R1233zd, while maintaining non-flammability and low toxicity, with improved cycle efficiency and reduced noise from high-speed operation.
Implementation Method 1
a centrifugal compressor along the vapor compression loop. The compressor comprises: a housing; an inlet; an outlet; an impeller; an electric motor coupled to the impeller to drive rotation of the impeller
Implementation Method 2
one or more refrigerant-lubricated bearings
Implementation Method 3
An indoor unit includes an indoor heat exchanger (heat absorption heat exchanger or evaporator in the cooling/air conditioning mode) and associated fan. The outdoor unit includes an outdoor heat exchanger (heat rejection heat exchanger in a cooling/air conditioning mode) and an associated fan
Data Source
AI summary
A system (20; 300) comprises: a vapor compression loop (38; 338); a low-pressure or medium-pressure refrigerant in the loop; a centrifugal compressor (42) along the vapor compression loop and comprising: a housing (120); an inlet (44); an outlet (46); an impeller (140); an electric motor (122) coupled to the impeller to drive rotation of the impeller; and one or more refrigerant-lubricated bearings (130, 132).