Air-conditioning apparatus and method of installing the same
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Solution Overview
Problem
Existing air-conditioning systems using flammable refrigerants face challenges in safely managing refrigerant leaks, particularly in high heat load applications like commercial kitchens, where the current methods may excessively restrict refrigerant amounts, making it difficult to satisfy safety standards due to the lack of consideration for leak speed in existing formulas.
Innovation Solution
An air-conditioning apparatus that calculates and secures an effective refrigerant amount using the formula M≤α×G−β×h0×A, where M is the refrigerant amount, G is the maximum leak speed, h0 is the installation height, and A is the installation floor space, with constants α and β determined by experiments to ensure safety and prevent flammable area generation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the refrigerant amount is restricted according to the existing formula (mmax=2.5×(LFL)1.25×h0×(A)0.5), then safety is improved, but the refrigerant amount becomes excessively restricted making it difficult to satisfy safety standards in high heat load applications
Solution Approach 1:
The patent changes the parameters of the safety calculation formula by introducing the leak speed parameter G and modifying the relationship between refrigerant amount, installation height, and floor space. The new formula M≤α×G−β×h0×A transforms the safety assessment from a static calculation to one that dynamically considers refrigerant leak characteristics, allowing for optimized refrigerant charging amounts that maintain safety while meeting performance requirements in high heat load applications
Solution Approach 2:
The patent creates a new safety assessment model that copies and adapts the structure of existing safety formulas but incorporates additional critical parameters. By replicating the formula structure while adding leak speed consideration, the invention produces a more accurate safety evaluation that prevents excessive refrigerant restriction
2Productivity
If the refrigerant amount is increased to satisfy high heat load requirements, then operational efficiency is improved, but the risk of flammable area generation increases
Solution Approach 1:
The patent implements a feedback mechanism by incorporating the leak speed parameter G into the refrigerant amount calculation. This creates a closed-loop safety assessment where the potential harmful effect (leak rate) is measured and used to adjust the refrigerant charging amount, allowing operational efficiency to be optimized while maintaining safety through continuous parameter evaluation
Solution Approach 2:
The patent performs preliminary safety assessment by calculating the maximum allowable refrigerant amount M before system operation using the formula M≤α×G−β×h0×A. This preliminary calculation considers the specific leak characteristics of the installation environment, allowing the system to be pre-configured with the optimal refrigerant amount that ensures both operational efficiency and safety before actual use
Data Source
AI summary
An indoor unit of an air-conditioning apparatus is installed at an installation height of h0 or more in an installation floor space A [m2] and a refrigerant amount M [kg] to be filled falls within (formula) M≤α×G−β×h0×A.