Greenhouse Screen Porous Yarn Network Condensation Management
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Solution Overview
Problem
Greenhouse screens face challenges in preventing condensation drop formation, maintaining energy efficiency, and durability, especially in large commercial installations with vegetable crops, where high light input, low light loss, and frequent replacement are critical, while also needing to manage air humidity and prevent algae formation.
Innovation Solution
A greenhouse screen made from flexible, translucent plastic sheeting with a yarn network that allows vapor and small water passage, using varying needle thicknesses and spacings to control moisture transfer, and a stitching technique that ensures strength and stability, allowing for capillary binding and evaporation while preventing convection and algae formation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If a greenhouse screen is made tight to prevent convection and maintain energy efficiency, then energy saving is improved, but condensation drop formation increases
Solution Approach 1:
The screen is constructed with a porous structure containing numerous capillaries that allow controlled water vapor and condensate passage. This porous design enables the screen to maintain tightness for energy efficiency while simultaneously providing pathways for condensation management through capillary action, preventing harmful water drop accumulation.
Solution Approach 2:
The capillary network acts as an intermediary mechanism between the tight screen structure and condensation management. The capillaries serve as intermediate pathways that bind and transport condensate through the screen material, mediating between the need for tightness (energy saving) and the need to prevent water accumulation.
2Object-affected harmful factors
If the screen allows water vapor passage to prevent condensation, then condensation management is improved, but convection increases leading to energy loss
Solution Approach 1:
The screen utilizes a porous structure with capillaries sized to allow water vapor and small water molecules to pass through via diffusion and capillary action, while the overall tight structure maintains resistance to bulk air convection. This selective permeability enables condensation management without significant energy loss.
3Reliability
If the fabric is made strong and unshrinkable for large greenhouse areas, then reliability is improved, but handling and installation become more difficult
Solution Approach 1:
The screen is manufactured in modular segments or panels that can be easily transported and installed. This segmentation allows the large-area, high-strength fabric to be handled in manageable sections while maintaining overall reliability and unshrinkability when assembled into the complete greenhouse covering.
4Volume of moving object
If the screen is compressed into a narrow bundle for storage, then space efficiency is improved, but fabric damage increases
Solution Approach 1:
The screen material incorporates dynamic properties including flexibility and elastic recovery, allowing it to be compressed into narrow bundles for storage while maintaining structural integrity. The material can dynamically adapt to compression forces during storage and then recover its original shape during installation, preventing permanent damage.
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 solution provides a cost-effective, energy-efficient screen that maintains high light input, prevents condensation drops, and ensures durability, allowing for easy handling and installation, reducing labor costs and minimizing light and energy losses.
Implementation Method 1
water vapour must be able to pass through the fabric
Implementation Method 2
the fabric to incorporate a function which can deal with temporary condensation situations by capillary binding and transfer from the underside to the upper side
Implementation Method 3
allows water vapour and small amounts of water to pass through it
Data Source
Figure 1
Figure 2
AI summary
The present invention relates to a greenhouse screen or the like which is intended for substantially horizontal application and for thermal stratification of the air space under a greenhouse roof, and which prevents drop formation from condensation. The invention also relates to a method for making this screen. The screen comprises webs of sheeting which are joined together edge to edge (or overlapping) by sewn-in threads in longitudinal and transverse directions which constitute a network on at least one side of the sheeting.