Heat pump type heat source apparatus
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Solution Overview
Problem
Conventional heat pump type heat source apparatuses face challenges in maintaining the compression ratio within the usage range during low differential pressure operation without using pressure sensors, which affects reliability, manufacturability, and manufacturing cost.
Innovation Solution
A heat pump type heat source apparatus that includes a refrigeration cycle with a compressor, heat exchangers, and temperature sensors, where a controller adjusts the compressor's operating frequency based on detected temperatures to maintain the compression ratio within the usage range during low differential pressure operations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If two pressure sensors are provided to control compression ratio during low differential pressure operation, then the compression ratio can be maintained within usage range, but the reliability decreases and manufacturing cost increases due to sensor failure risk and additional components
Solution Approach 1:
The patent extracts the pressure sensing function from physical pressure sensors and relocates it to the controller through calculation. The controller computes suction pressure and discharge pressure by subtracting pressure loss from measured temperatures, eliminating the need for physical pressure sensors and their associated reliability issues.
Solution Approach 2:
The patent replaces the mechanical pressure sensing system with a thermal measurement and calculation system. Temperature sensors measure refrigerant temperatures, and the controller uses these measurements along with predetermined pressure loss values to calculate pressure parameters, substituting mechanical sensors with a computational approach.
2Measurement precision
If pressure sensors are installed to detect refrigerant pressure for compression ratio control, then accurate pressure measurement is achieved, but the manufacturing cost increases due to additional sensor components
Solution Approach 1:
The patent creates a virtual copy of pressure measurement through calculation rather than direct physical measurement. The controller calculates pressure values based on temperature measurements and predetermined pressure loss characteristics, producing accurate pressure data without requiring physical pressure sensors.
Solution Approach 2:
The patent substitutes expensive mechanical pressure sensors with cheaper temperature sensors and computational algorithms. The temperature-based pressure calculation method reduces manufacturing costs while maintaining measurement precision through the relationship between temperature and pressure in the refrigeration cycle.
3Use of energy by moving object
If the compressor operating frequency is decreased to maintain heat medium temperature near setting temperature, then energy efficiency improves, but the compression ratio falls outside usage range during low differential pressure operation
Solution Approach 1:
The patent implements a feedback control system where the controller continuously monitors temperature measurements, calculates compression ratio in real-time, and adjusts compressor operating frequency accordingly. This feedback mechanism ensures the compression ratio remains within the usage range while optimizing energy efficiency during low differential pressure operation.
Solution Approach 2:
The patent dynamically adjusts the lower limit of compressor operating frequency based on calculated compression ratio. When operating in low differential pressure conditions, the controller raises the frequency lower limit to prevent compression ratio from falling outside the usage range, allowing flexible adaptation to changing operating conditions.
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 solution allows the heat pump apparatus to maintain the compression ratio within the acceptable range without pressure sensors, reducing the risk of compressor failure and improving reliability and efficiency, while also reducing manufacturing costs.
Implementation Method 1
a temperature sensor installed in the refrigeration cycle, and configured to detect a temperature of the refrigeration cycle
Implementation Method 2
a refrigeration cycle that includes a compressor
Implementation Method 3
a first heat exchanger, an expansion device, and a second heat exchanger
Data Source
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AI summary
A heat pump type heat source apparatus includes: a refrigeration cycle provided with a compressor, a first heat exchanger, an expansion device, and a second heat exchanger; a heat-medium flow passage that is connected to the first heat exchanger of the refrigeration cycle as a flow passage of a heat medium circulating via the first heat exchanger; a temperature sensor installed in the refrigeration cycle, and configured to detect a temperature of the refrigeration cycle; and a controller configured to change a lower limit of an operating frequency of the compressor based on a temperature detected by the temperature sensor so that a compression ratio of the compressor is maintained within a usage range, when the compressor is driven under low differential pressure operation in which difference between suction pressure and discharge pressure is small.