Adjustable Condenser Control for Faster Heat Pump Dryer Startup
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Solution Overview
Problem
Heat pump dryers using mechanical refrigeration cycles face challenges in accelerating the start-up transient period and achieving efficient drying, as they typically rely on electric resistance heaters or gas burners, which are inefficient and wasteful, and existing systems do not effectively manage the refrigeration cycle's thermodynamic state to optimize drying performance.
Innovation Solution
Incorporating an adjustable condenser with a refrigerant input and output component, a transient coil area, and supplemental coil area, along with flow valves, and using an auxiliary heater to pre-load the evaporator, which adjusts the condenser's surface area during different phases of the drying cycle to accelerate the start-up and optimize refrigeration cycle efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If an adjustable condenser is used to increase surface area during steady state drying, then drying efficiency is improved, but device complexity increases
Solution Approach 1:
The condenser is divided into multiple sections with different surface areas that can be selectively activated. The adjustable condenser includes a first section and a second section, where only the first section operates during transient periods and both sections operate during steady state periods, allowing efficiency optimization without requiring a completely complex redesign.
Solution Approach 2:
The condenser surface area is made dynamically adjustable based on operating conditions. A controller monitors the drying cycle phase and adjusts the active condenser surface area accordingly - using only the first section during transient periods and both sections during steady state periods, thereby optimizing performance while managing complexity.
2Loss of time
If the condenser surface area is decreased during start transient period, then the transient period is accelerated, but drying capacity is reduced
Solution Approach 1:
During the start transient period, the system preliminarily activates only the first section of the condenser to quickly establish stable operating conditions and accelerate the transient response. Once steady state is achieved, the second section is activated to provide full drying capacity, thus combining fast startup with high productivity.
Solution Approach 2:
The condenser operates in periodic phases: during transient periods, only the first section is active to accelerate startup; during steady state periods, both sections are active to maximize drying capacity. This periodic adjustment of active surface area resolves the contradiction between fast startup and high productivity.
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 significantly reduces drying time by elevating refrigerant cycle pressures and temperatures, improving refrigeration cycle efficiency, and allowing for better control of the thermodynamic state, thereby enhancing the drying process while minimizing energy consumption.
Implementation Method 1
a condenser of adjustable surface area... adjusting the condenser to increase surface area during a steady state drying rate period of the cycle
Implementation Method 2
a mechanical refrigeration cycle arrangement having a working fluid and an evaporator, a condenser of adjustable surface area, a compressor, and an expansion device
Implementation Method 3
a mechanical refrigeration cycle arrangement having a working fluid and an evaporator, a condenser of adjustable surface area
Data Source
AI summary
An apparatus includes a mechanical refrigeration cycle arrangement having a working fluid and an evaporator, a condenser of adjustable surface area, a compressor, and an expansion device, cooperatively interconnected and containing the working fluid. The apparatus also includes a drum to receive clothes to be dried, a duct and fan arrangement configured to pass air over the condenser and through the drum, a sensor located to sense at least one parameter, and a controller coupled to the sensor, condenser and/or the compressor. The controller is operative to adjust the condenser to increase surface area during a steady state drying rate period of the cycle, and adjust the condenser to decrease surface area during a start transient period of the cycle, wherein adjusting the condenser to decrease surface area during a start transient period of the cycle accelerates the start transient period of the cycle.