Zone Heating Systems Research Articles

Effects of different root zone heating systems on the microclimate and crop development in solar greenhouses

Effects of different root zone heating systems on the microclimate and crop development in solar greenhouses

Analysis of Smart Zone Heating in Different Heating Systems

The basic concept in the design of buildings with zero energy consumption is, in addition to high-quality thermal properties of the building envelope, also a correct and efficient system of heating and hot water preparation in residential buildings. One of the basic concepts when designing heating systems is a zone heating system. It is a system that brings effective regulation according to heating zones. In practice, the question sometimes arises as to whether zone regulation of individual rooms in small family houses is necessary. That is whether in such buildings, zone heating is not an unnecessary investment cost. In this paper, we analyze the effect of zone heating in two types of heat transfer systems on the internal operating temperature in the individual analyzed zones, which are interconnected by an internal partition structure. It is a verification that even in smaller spaces, zone heating has a significant potential for energy savings.

Investigation of a root zone heating system for greenhouse seedling and its effects on micro-environment

Under the extremely cold climatic condition, crops have to survive severe heat stress conditions, even if they are being kept in greenhouses. In the winter and spring of North China, the air and soil temperature is low inside the greenhouse, and when using a traditional heating system, the energy consumption is high. This paper reports on a study of different design solutions for a root zone heating system based on a kind of low temperature radiation material. Root zone heating systems offer increasing crop quality and productivity. A novel type of heat preservation and root zone heating system was applied in greenhouse seedling. And through multiple experiments, the effect of the root zone heating system on the ambient environment and seedbed surface was studied, and the heat preservation effect and heating uniformity were discussed. Results show that single-layer film covering on the root zone heating system can make the average temperature at night increase 1°C. And the average seedbed surface and substrate temperature can increase 11.3°C and 5.2°C, respectively. In conclusion, the root zone heating system can effectively improve the environmental temperature of seedling and the uniformity of heating is high, which provides a strong guarantee for high-quality seedling cultivation. Keywords: greenhouse, root zone heating system, micro-environment, seedling, substrate temperature, air temperature DOI: 10.25165/j.ijabe.20201306.5905 Citation: He F, Hou Y, Li K, Wei X M, Liu Y Q. Investigation of a root zone heating system for greenhouse seedling and its effects on the micro-environment. Int J Agric & Biol Eng, 2020; 13(6): 47–52.

Investigation of a root zone heating system for greenhouse seedling and its effects on micro-environment

Under the extremely cold climatic condition, crops have to survive severe heat stress conditions, even if they are being kept in greenhouses. In the winter and spring of North China, the air and soil temperature is low inside the greenhouse, and when using a traditional heating system, the energy consumption is high. This paper reports on a study of different design solutions for a root zone heating system based on a kind of low temperature radiation material. Root zone heating systems offer increasing crop quality and productivity. A novel type of heat preservation and root zone heating system was applied in greenhouse seedling. And through multiple experiments, the effect of the root zone heating system on the ambient environment and seedbed surface was studied, and the heat preservation effect and heating uniformity were discussed. Results show that single-layer film covering on the root zone heating system can make the average temperature at night increase 1°C. And the average seedbed surface and substrate temperature can increase 11.3°C and 5.2°C, respectively. In conclusion, the root zone heating system can effectively improve the environmental temperature of seedling and the uniformity of heating is high, which provides a strong guarantee for high-quality seedling cultivation. Keywords: greenhouse, root zone heating system, micro-environment, seedling, substrate temperature, air temperature DOI: 10.25165/j.ijabe.20201306.5905 Citation: He F, Hou Y, Li K, Wei X M, Liu Y Q. Investigation of a root zone heating system for greenhouse seedling and its effects on the micro-environment. Int J Agric & Biol Eng, 2020; 13(6): 47–52.

An Investigation of a Root Zone Heating System and Its Effects on the Morphology of Winter-Grown Green Peppers

The winter season in Nanjing is from December to February, with extremely low temperature and high humidity due to seasonal snowfall. During these extreme cold climatic conditions, plants have to survive severe heat stress conditions, even if they are being kept in greenhouses. The objective of this study was to investigate a heating system that can provide heat directly to the root zone instead of heating the entire greenhouse, which is a viable option to reduce energy consumption. Root zone heating could be an effective alternative for the sustainable development of plants during the winter. A novel type of root zone heating system was applied to evaluate the energy consumption during different greenhouse ambient temperature conditions, the effects of root zone heating systems on pepper plant morphology, and heat transfer rates to plant canopy in the greenhouse. The temperature treatments in root zone heating system were T-15, T-20, T-25, T-30, and a control treatment (TC) at 15 °C, 20 °C, 25 °C, and 30 °C, respectively, while TC received no heat. A simulation study was carried out to validate the root zone temperature. The results of the current investigation revealed that energy consumption has an inverse relationship to the ambient temperature of the greenhouse, while temperature gradients to the plant canopy observed from the lower to the upper part of the plant and the upper canopy experienced less temperature fluctuation as compared to the lower part of the plant. The results also showed that treatment T-20 had the maximum in terms of the leaf dry weight, stem diameter, and the number of leaves, while T-25 showed the maximum root dry weight and stem dry weight; T-30 and T-15 had minimum dry weights of plant segments among all treatments. Control treatment (TC) showed a minimum dry mass of plant. The root zone heating with optimal root zone temperature was found to be a viable and adaptable option as this leads to improved energy consumption patterns for the sustainable growth and development of plants in greenhouses during extremely low temperatures.

Performance Evaluation of Root Zone Heating System Developed with Sustainable Materials for Application in Low Temperatures

The proposed system was developed to help the farmers of the Yangtze River Delta to grow greenhouse plants over winter, as the region has very low winter temperatures. For this reason, the experiment was undertaken during winter in extremely low temperatures to obtain optimal results. Keeping in mind the importance of sustainable practices, the authors developed the system using sustainable materials. The system was heated for 6 hours and then the hourly heat transfer rates were measured for 12 hours. The power consumption data of the heating system during different ambient temperatures were collected. Additionally, a simulation model of the heating system was developed using the COMSOL Multiphysics 5.3a package. The heat transfer in a porous media model was used in this study. Finally, the simulation results obtained from the COMSOL Multiphysics 5.3a package were analyzed and compared to the experimental results; these results were found to be in good agreement, thus authenticating the simulation model. After analyzing the data obtained from both methods, the power consumption of the heating system during different ambient temperature conditions were also calculated, which ranged from 15.73 W to 70.02 W in the simulated method and 28.2 W to 91.2 W in the experimental method. It was found that the root zone temperature remained in the range of 0–35 °C. This range of root zone temperature is suitable for many greenhouse horticultural crops such as tomato, cucumber, pepper, strawberry, lettuce, etc. The optimal root zone temperatures of many greenhouse horticultural plants are verified by many researchers.

Analysis of the technical, environmental and economic potential of phase change materials (PCM) for root zone heating in Mediterranean greenhouses

Root zone heating systems offer increasing crops quality and productivity. However, these systems are based on the use of nonrenewable fuels. This paper reports on a study of different design solutions for a root zone heating system, based on thermal energy storage with PCM. The objective of the study was to define, through multiple experiments, the most efficient PCM melting/freezing temperature and location with respect to the substrate (i.e., under the substrate) for the application under study; as well as, to determine the system’s environmental and economic feasibility, with life cycle assessment and life cycle cost methodologies. Results show that the best melting temperature for the application under study is 15 °C. To increase the efficiency of the system, PCMs may be macro encapsulated and wrap the entire perlite bag. Moreover, it seems that PCMs are far to substitute conventional root zone heating systems because it does not provided enough heat during nights. Nevertheless, PCMs can help to reduce the operation time of conventional systems. Based on one night results it seem that PCM could provide annual saving of between 22 and 30 kg of eq. CO2/ha·day. However, it does not seem to be feasible if PCM prices (8€/kg) do not decrease significantly.

LCA & LCCA of a PCM application to control root zone temperatures of hydroponic crops in comparison with conventional root zone heating systems

The present study analyzes the environmental and economic performance of the use of PCM as a root zone temperature control system in substitution of conventional gas, oil and biomass heating systems by using life cycle assessment (LCA) and life cycle accounting (LCCA) methodologies. This study is focused on the possible application of these systems in a multitunel greenhouse situated in southern Spain. For the study was assumed a crop productivity increase of 20% when root zone temperature control systems are applied. Results showed that gas, oil and biomass conventional heating systems reduce farmer's net benefit and increase the environmental impact of each kg of produced tomato despite the assumed increase of productivity. Significant environmental and economic benefits are obtained for PCM in relation with the use of gas and oil root zone heating systems. In relation with biomass, heating system economical advantage is obtained but environmental results are similar. When analyzing PCM scenario in comparison with conventional production without heating systems, no significant positive results were obtained. To reduce tomato production CO2 emissions and costs, yield production should increase 8.5% and 18% respectively.

Energy Saving Benefit Evaluation of Zone and Time Control Heating for One College

In consideration of the current situation that college buildings are still heated as normal without occupancy,causing energy waste,the on-duty heating will be adopted in college buildings without occupancy under the premise to ensure the indoor comfort requirements.In the case of one college, the energy saving rate and cost saving rate were evaluated for college buildings that used zone and time control heating systems for buildings of different functions.The results show that the annual heating energy saving rate is 34.5%,and the annual heating cost saving rate is 51.5%. In similar collage buildings, 5.48kg of standard coal and 14.43Yuan per square meter of structure area can be saved per year if using zone and time control heating.

Ibaraki Prefectural Kashima Soccer Stadium provided by controlled root zone heating system and installed inside & outside sprinkler system for turfgrass maintenance

Ibaraki Prefectural Kashima Soccer Stadium provided by controlled root zone heating system and installed inside & outside sprinkler system for turfgrass maintenance

Investigation of the wafer temperature uniformity in an omvpe vertical rotating disk reactor

Measuring the wafer temperature uniformity is one of most difficult problems in the development of organometallic vapor phase epitaxy (OMVPE) equipment. Until recently, the lack of a good experimental technique limited the understanding of OMVPE rotating disk reactor (RDR) thermal dynamic. We have developed a rotating wafer thermal imaging technique, which for the first time allows a real-time experimental investigation of the temperature distribution across the wafer in an RDR under realistic deposition conditions. This technique allows investigation on how process parameters such as the growth temperature (from 650 to 800°C), reactor pressure (from 10 to 620 Torr), reactant flow (from 2 to 30 slm), and wafer carrier rotation speed (from 300 to 1030 rpm) affect the wafer temperature uniformity. This information has allowed us to establish under which conditions single or multi-zone heating should be used in the OMVPE reactor. A wafer temperature uniformity of better than 1°C was demonstrated for both an optimized single zone heating system under a selected combination of process parameters, and for a two-zone heating system over a wide range of the process parameters.

On optimal zone heating and energy conservation in passive solar buildings

Strategies for reducing the energy consumption of buildings include energy conservation, passive solar, and zone heating systems. In this paper, the constrained and global interzonal and overall building load coefficients, and the optimal mix of energy conservation, passive solar and zone heating are calculated as a function of economic and thermal parameters. Results are presented for the sensitivities of the optimal cost fractions to changes in the cost of passive solar and zone heating. For representative costs, the analysis indicated the largest component is energy conservation, followed by passive solar, zone heating and interzonal insulation.

Optimization and Design of Zone Heating Systems, Energy Conservation, and Passive Solar

This paper addresses the problem of determining the optimal mix of energy conservation, passive solar, and zone heating systems in residential buildings. Analytic solutions to constrained and global optimization problems are presented. This work draws upon the Lagrangian multiplier technique used in related studies of energy conservation and passive solar design. Graphs are presented showing the optimal cost fractions for energy conservation, passive solar, and a zone heater as a function of the initial cost constraint, for a reference building in Dodge City, Kansas. The use of a zone heater is shown to reduce the annual energy requirements for space heating, and increase the life cycle savings. Also presented are design curves for the required zone heater capacity as a function of the thermal time constant for a given zone, heater response time, and interzonal heat transfer. Finally, design curves for the zone mean radiant temperature as a function of zone size, zone heater temperature, zone heater area, and interzonal heat transfer are presented.