Research Project: Water curtains and soap bubbles for energy efficiency and heating of greenhouses with low water temperatures: Development and calibration of new TRNSYS model for energy analysis and system sizing

Project leader
Tomas Persson
Project Members
Project Period
Project Status
A new concept for low-temperature heating of greenhouses has been evaluated in Dalarna University's climate chamber in 2021. The concept involves heating with enclosed water curtains between two plastic foils where the space is filled with soap bubbles to minimize heat losses at night. Both water curtains and bubbles are techniques that have been developed for several decades, but the combination is new and it provides the opportunity to compensate for all heat losses through the greenhouse with a water temperature of only 5 ° C above the desired greenhouse temperature. Thus, it is possible to use residual heat efficiently for cultivation purposes. For a functioning cultivation system, additional heating systems, cooling, dehumidification, carbon dioxide supply and lighting are needed. A challenge in closed energy-efficient heating systems is that the need for cooling or ventilation, which becomes very electricity-intensive if fans are to be used. Energy-efficient cooling can be water-borne cooling from snow layers, lakes or ground.

In order to develop and optimize the energy solutions, this project proposes the development of a TRNSYS model that can be used for energy analysis and dimensioning of complementary systems. The model will be calibrated against measurement data on a real model that was installed in a climate chamber. The model is supplemented with a simple model for transpiration from the cultivation culture, a model that calculates electricity requirements for lighting with LED and a model for complementary heating, cooling and dehumidification systems. The model is then used to dimension heating, dehumidification and cooling systems and analyze annual energy and power requirements as well as temperature requirements for the heating and cooling water.
Energieffektiva växthus; lågtemperaturuppvärmning; såpbubblor, Energy efficient greenhouses; low temperature heating; soap bubbles; liquid foam
Research Profile
Energy and Built Environments
Energy Technology
J. Gust. Richert stiftelse