Ground-Loop Greenhouse Heat Exchange for Temperature and Humidity Control
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Solution Overview
Problem
Greenhouses in high elevation and equatorial regions face significant temperature fluctuations, leading to stress and reduced growth for plants due to inadequate temperature control systems, which are often expensive and inefficient, and fail to maintain optimal humidity levels.
Innovation Solution
A greenhouse design incorporating a Ground to Air Heat Transfer (GAHT) system, which uses a thermal exchange fluid to regulate temperature through a ground loop and air manifolds, combined with a reflective and insulated structure to optimize light intake and thermal management, including phase change materials and a multi-source ground-to-air heat exchange system for efficient climate control.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If conventional HVACD systems are used for temperature control, then temperature regulation is achieved, but operating costs increase and moisture removal capacity is limited
Solution Approach 1:
The greenhouse system uses phase change materials (paraffin wax) that automatically absorb and release heat through phase transitions without requiring external energy input. The materials self-regulate temperature by melting during the day to cool the greenhouse and solidifying at night to provide heat, eliminating the need for continuous HVAC operation
Solution Approach 2:
The patent employs phase change materials (PCM) with melting points between 10-50°C that undergo phase transitions to store and release thermal energy. The PCM absorbs heat when melting during daytime heating and releases heat when solidifying during nighttime cooling, providing passive temperature regulation
2Temperature
If conventional HVACD systems are used for temperature control, then temperature regulation is achieved, but moisture removal capacity is insufficient
Solution Approach 1:
The phase change materials not only regulate temperature but also influence humidity control through their phase transition process. When PCM melts, it absorbs latent heat and affects the moisture balance in the greenhouse, working synergistically with the dehumidification system
3Illumination intensity
If greenhouse structure allows maximum sunlight intake, then photosynthesis is enhanced, but temperature becomes too high during the day
Solution Approach 1:
The phase change materials absorb excess solar heat during the day as they melt, preventing overheating while allowing maximum sunlight transmission. The PCM acts as a thermal buffer that captures heat energy without raising temperature, enabling high light intensity for photosynthesis
Solution Approach 2:
The system converts the harmful excess solar heat into useful thermal energy storage. The phase change materials absorb the excess heat that would otherwise damage plants, storing it during the day for later use during nighttime cooling
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 effectively moderates temperature and humidity within the greenhouse, promoting plant growth by maintaining optimal conditions, reducing energy costs, and enhancing light exposure, thereby supporting plant production in challenging climates.
Implementation Method 1
uses a thermal exchange fluid to regulate temperature through a ground loop and air manifolds
Implementation Method 2
A first heat pump may be configured to regulate the temperature of the greenhouse enclosure
Implementation Method 3
The inside surface of the north wall may comprise a light reflective surface so that sunlight entering from the south wall
Implementation Method 4
The north wall may comprise a phase change material that absorbs heat during the daylight hours and then emits heat into the greenhouse during the night
Implementation Method 5
A second heat pump may be configured to extract heat from the thermal exchange fluid to cool and dehumidify the greenhouse enclosure
Data Source
AI summary
A multi-source ground-to-air heat transfer system is configured to store thermal energy during a cooling/dehumidifcation mode of operation for future use during a heating mode of operation. The multi-source ground-to-air heat transfer system utilizes a ground loop that is configured under an enclosure, such as a greenhouse, and is in thermal communication with a thermal reservoir medium to conduct and store heat. A thermal exchange fluid is pumped through the ground loop and ground heat exchanger and may receive heat from a condenser during a cooling/dehumidification mode of operation and may liberate heat to the evaporator during a heating mode. The enclosure air may receive heat from the heat pump during a heating mode and may liberate heat to the evaporator during a cooling/dehumidification mode. The heat exchange system may employ a heat pump having a reversing valve to change the mode of operation.