Air-conditioning apparatus with temperature controlled pump operation
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Solution Overview
Problem
Air-conditioning systems using water or similar as a heat medium can freeze in certain environments, leading to pipe damage due to volume expansion, which existing technologies fail to adequately prevent.
Innovation Solution
An air-conditioning apparatus with a refrigeration cycle and a heat medium circuit that includes a compressor, refrigerant flow switching device, heat source side heat exchanger, expansion device, intermediate heat exchanger, pump, use side heat exchanger, and a controller that activates the pump to circulate the heat medium when outdoor temperatures drop below a predetermined level to prevent freezing, optimizing energy efficiency by minimizing unnecessary pump activations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If the circulation of the heat medium is stopped to achieve energy saving, then the conveyance power is reduced, but the heat medium may freeze and cause pipe damage
Solution Approach 1:
The controller activates the pump in advance when the outdoor temperature drops below a predetermined temperature, before the heat medium temperature reaches the freezing point. This preliminary action prevents freezing while avoiding unnecessary pump operation during mild conditions, thus resolving the contradiction between energy saving and freezing prevention.
2Reliability
If the pump is activated frequently to prevent freezing, then the reliability of freezing prevention is improved, but the energy consumption increases
Solution Approach 1:
The controller continuously monitors the outdoor temperature and compares it with the predetermined temperature threshold. The pump operation is controlled based on this feedback, activating only when necessary (when temperature drops below the threshold) and stopping when the temperature rises above it. This feedback mechanism ensures reliable freezing prevention while minimizing energy consumption by avoiding unnecessary pump activations.
3Reliability
If the pump operation is extended to ensure freezing prevention, then the safety margin is increased, but the energy saving effect is reduced
Solution Approach 1:
The controller activates the pump when the outdoor temperature drops below a predetermined temperature, which provides a safety margin before the heat medium reaches freezing temperature. This partial action (activating before actual freezing risk) is sufficient to prevent freezing while avoiding excessive action (continuous operation), thus achieving both reliable freezing prevention and energy saving.
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
Effectively prevents heat medium freezing, reducing the risk of pipe damage and achieving energy savings by controlled circulation of the heat medium, thereby enhancing the reliability and efficiency of the air-conditioning system.
Implementation Method 1
at least one intermediate heat exchanger (15a, 15b) which exchanges heat between the heat source side refrigerant and a heat medium different from the heat source side refrigerant
Implementation Method 2
exchanges heat between the heat source side refrigerant and a heat medium
Implementation Method 3
a use side heat exchanger (26) which exchanges heat between the heat medium and air related to an air-conditioned space
Implementation Method 4
exchanges heat between the heat medium and air
Implementation Method 5
at least one pump (21) which circulates the heat medium related to heat exchange in the intermediate heat exchanger (15a, 15b)
Data Source
AI summary
An air-conditioning apparatus includes a refrigeration cycle that includes an intermediate heat exchanger configured to exchange heat between a heat source side refrigerant and a heat medium different from the heat source side refrigerant. The apparatus further includes a heat medium circuit that includes at least one pump configured to circulate the heat medium in the intermediate heat exchanger. A controller in the apparatus further activates the pump to circulate the heat medium through the heat medium circuit when, during suspension of an air conditioning operation, the detected temperature of outdoor air is at or below a first predetermined temperature and a first predetermined period of time has elapsed since the pump was stopped.