Greenhouse Heating Research Articles

Geothermal sources and utilization practice in six countries along the southern part of the Pannonian basin

Data on thermal water sources with outflow temperature of 30 °C and above were analyzed from the N-ern parts of Bosnia and Herzegovina, Serbia and Croatia, S-ern parts of Hungary, W-ern parts of Romania, and NE-ern parts of Slovenia, altogether from an area of 99,347 km2. The overview identified 771 geothermal sources; only 7 were thermal springs. The average well depth is about 1.2 km. About 13% of wells are younger than 10 years, additional 17% below 30 years; while 26% are older than 50 years. Average thermal water outflow temperature is 54 °C being the highest, 170 °C, in Croatia. Most thermal water is produced from basin fill sediments—Lower and Upper Pannonian (Mio-Pliocene) loose sandstones which are tapped by 86% of wells. The rest appertains to basement rocks—fissured, fractured and karstified Paleozoic, Mesozoic and Middle Miocene metamorphic, carbonate and siliciclastic rocks. In total, 72% sources hold water rights, 6% mining rights, 2% geothermal rights and 1% has no rights. The permits allow much higher water abstraction as currently listed. Usage for bathing and balneology encompasses 24% of all active sources (155), some of these also with heating (23). 104 objects (16%) are used for heating, also district heating (13) and individual space heating (3). An additional 10% (70) are used in agriculture, mainly greenhouse heating. There are 41 reinjection wells (5%). It is primarily in Hungary that drinking water (17%), industrial usage (5%) and monitoring wells (2%) are also common.

Effects of Infrared Radiation on Eggplant (Solanum melongena L.) Greenhouse Cultivation and Fruits' Phenolic Profile.

The implementation of Infrared (IR) radiation in heated greenhouses possesses the advantage of high directional control and focused compensation of energy losses, appropriate for creating local microclimate conditions in highly energy-consuming systems, such as greenhouses. Moreover, it can efficiently maintain favorable environmental conditions at the plant canopy. The present study studies the application of Infrared (IR) heating in an experimental greenhouse with eggplant (Solanum melongena L.) cultivation. The experimental results are presented from a full cultivation period inside two identical, small scale experimental greenhouses, with IR and forced air heating system, respectively. The effects of IR heating over plant growth parameters, including the yield of the fruits as well as the total phenolic content and the antioxidant profile of eggplants fruits’ extracts are measured and discussed. The results indicate a greater uniformity production in the IR heating greenhouse in terms of antioxidant and radical scavenging activities, as well as the total phenolic content. Moreover, the phenolic profile of eggplant fruits from both greenhouses revealed the existence of numerous bioactive compounds, some of which were only characteristic of the eggplant fruits from IR heated greenhouses.

Thermal Energy Storage Technology for Application in Transport Refrigeration

This paper reviews the use of an alternative refrigeration system in refrigerated vehicles by using thermal energy storage systems. The application of thermal energy storage systems in transport refrigeration focusing particularly on latent heat phase change materials PCMs that have been used in recent years is reviewed. The majority of PCMs are found in building applications for space heating and cooling, greenhouse heating applications, solar cookers, and storage of solar energy for water heating. The focus of this work is on latent heat storage (LHS) materials for road transport refrigeration and their benefits in the refrigeration of perishable foodstuffs for short- and long-distance transportation. The benefits of using LHS materials over a conventional mechanical vapour compression system are explored. This paper also centres on the need to develop new PCMs with high thermal cycles and minimal degradation to ensure effective performance in the transport refrigeration industry. Criteria for selecting suitable PCMs for different applications were summarised, and classification of PCMs based on their melting temperature and latent heat were tabulated. Heat transfer materials for increasing PCM performance were analysed as well as the effect of container material corrosion on PCM stability. The different thermal techniques for determining the properties of PCMs were summarised, and the accuracy of each technique was explored based on similar research work by other researchers. The PCMs that have been used in transport refrigeration as well as the thermo-physical criteria that are needed for different applications were analysed.

Combined cooling heating and power systems in greenhouses. Grassroots and retrofit design

Modern greenhouses are good candidates for combined cooling, heating and power generation (CCHP) systems. An analytical framework to assess the affordability of such systems for two different problems, is proposed; (a) the grassroots problem, i.e. the CCHP system is designed along with the greenhouse, and, (b) the retrofit problem, i.e. the addition of a CHP unit to an existing greenhouse. As a case study, the analysis is applied in three locations of Greece (North, Central, South) with different meteorological conditions, for two traditional products (tomato, cucumber). The results indicate that cogeneration is a cost-effective solution improving the economic and energetic efficiency of the facility. Furthermore, with the use of active cooling, the operating period of the greenhouse is increased, which significantly improves the cashflow. Product cultivation parameters and climatic conditions affect to a significant degree the overall performance. It is proved that the combined use of a CCHP and a conventional gas boiler for heating, is more profitable for tomato cultivation, achieving ROI 23%, 28%, and 27%, in North, Central and South Greece, respectively. The sensitivity of the investment’s feasibility is quantified in regards to energy prices, and pricing policies, which is one of the most important factors.

HEALTH AND SAFETY IN THE MECHANICAL ENGINEERING WORKPLACE

Risk assessment is the systematic recording and evaluation of all factors in the work process that can cause occupational injuries, illnesses or health damage. It can identify the options, ways of preventing, eliminating and reducing risks.The risk assessment considers the work organization, work processes, raw materials and materials used in technological and work processes, personal protective equipment and equipment at work, as well as other elements that may cause risk of personal injury, health damage or illness of the employee.The primary objective of occupational risk assessment is the protection, safety and health of employees.Risk assessment helps to minimize the risk of employees being compromised during work process activities. It also helps to maintain the efficiency of the business activity.A risk assessment act is an act containing a description of the work process with an assessment of the risk of injury and / or damage to workplace health in the work environment and measures to eliminate or reduce risks in order to improve safety and health at work.This act determines the possible types of hazards and harms in the workplace, assesses the risk of injury at work or health damage of the employee, determines ways and measures to eliminate them, or reduce their risk to minimum.Mechanical engineers design machines and tools, organize their production and handle their exploitation. They are experts for propulsion engines, vehicles and vessels, process and power plants, load-bearing structures. As designers, they design a product or manufacturing process so it can best meet the requirements and functions they need. In a process of designing a product, they take available raw materials and available production technology, and if they design the production process, they are guided by the type of input material and processing technology. Mechanical engineers in manufacturing plan, manage and supervise the production of machinery and plant. They systematically test the manufactured components, because they depend on the efficiency, reliability and safety of the whole system. For quality assurance, they constantly carry out tests and measurements of input materials and finished products with measuring instruments.This work is based on an analysis of the position of a mechanical engineer in the company named "Flamma-Systems Ltd." based in Nis. The company employs mechanical engineers and it deals primary with manufacturing of high-power boilers for heating greenhouses and buildings. The main market for this company is Sweden.

Analysis and performance assessment of coal-fired based integrated energy system for multigeneration

ABSTRACT The performance analysis of a multigeneration (MG) energy system integrated into a conventional coal-fired power plant was evaluated and discussed according to the data measured in the existing steam power plant. The multigeneration energy system in the present work consists of four subsystems, namely Organic Rankine Cycle (ORC), Vapor Compression Refrigeration (VCR) System, Thermal Vapor Compression Desalination Plant (TVCDP) and Greenhouse Heating (GH) System. The thermodynamic analysis was performed through energy and exergy analyses associated with the efficiencies of the subsystem as well as the multigeneration plant. In addition, environmental impact analysis was carried out to calculate CO2 emission of the overall system to evaluate the effect of emissions caused by the energy systems. The results revealed that when the conventional steam power plant became multigeneration, the exergy efficiency increased from 39.1% to 39.84% and energy efficiency increased from 41.5% to 42.29%. Four subsystems were integrated into the existing steam power plant to reduce CO2 emissions from 230 kg/MWh to 225 kg/MWh.

Economic performance evaluation of an active solar heat storage-release system for heating Chinese Solar Greenhouses

In this study, the economic and environmental performance of four active solar heat storage-release (AHS) systems compared with four other conventional heating systems (as practical options in northern China) were investigated in an experimental test of their ability to store energy during the daytime and heat a Chinese solar greenhouse (CSG) at night during the cold winter in northern China. The case-4 AHS performed best in terms of economic performance compared with the other three designs and four other conventional heating systems. However, future investigations of the long-term performance and environmental impact of AHS heating in greenhouses are needed and further improvements must be developed.

Determination of Thermal Radiation Emissivity and Absorptivity of Thermal Screens for Greenhouse

Greenhouse farmers often use thermal screens to reduce greenhouse heating expenses during the winter, and for shade during hot, sunny days in the summer, as it is an inexpensive solution to temperature control relative to other available options. However, accurate measurements of their emitted and absorbed radiations are important for the selection of suitable screens that offer maximum performance. Material’s ability to save energy is highly dependent on these properties. Limited studies have investigated the measurement of these properties under natural conditions, but they are only applicable to materials having partial porosities. In this work, we describe a new radiation balance method for determining emissive power and absorptive capacity, as well as reflectivity, transmissivity and emissivity of materials having complete and partial transparency by using pyrgeometer and net radiometer. In this study, four materials with zero porosity, were tested. The emissivity value of PE, LD-13, LD-15 and PH-20 was 0.439±0.020, 0.460±0.010, 0.454±0.004, and 0.499±0.006, respectively. All tested samples showed high emitted radiation as compared to absorbed radiation.

The EU and its Arctic spirit: Solving Arctic climate change from home?

Dealing with climate change and developing the Arctic sustainably are often seen as both binary and contradictory sets of challenges. The EU is in a unique position in Arctic affairs: unlike non-Arctic states, it is part of and linked to the region. However, the EU is at risk of missing the opportunity to be a leader in setting standards for a coherent and sustainable approach for the region. The Arctic is often used as a symbol for global climate change and, conversely, climate change is also used as a reason for more Arctic engagement. Yet, the roots of global heating—greenhouse gas emissions—mostly originate from outside the region. This article asks whether the path towards more EU–Arctic involvement should start closer to home.

Optimization of Greenhouse Thermal Screens for Maximized Energy Conservation

In this work, we proposed a Building Energy Simulation (BES) dynamic climatic model of greenhouses by utilizing Transient System Simulation (TRNSYS 18) software to study the effect of use of different thermal screen materials and control strategies of thermal screens on heat energy requirement of greenhouses. Thermal properties of the most common greenhouse thermal screens were measured and used in the BES model. Nash-Sutcliffe efficiency coefficients of 0.84 and 0.78 showed good agreement between the computed and experimental results, thus the proposed model appears to be appropriate for performing greenhouse thermal simulations. The proposed model was used to evaluate the effects of different thermal screens including; Polyester, Luxous, Tempa, and Multi-layers, as well as to evaluate control strategies of greenhouse thermal screens, subjected to Daegu city, (latitude 35.53 °N, longitude 128.36 °E) South Korea winter season weather conditions. Obtained results show that the heating requirement of greenhouses with multi-layer night thermal screens was 20%, 5.4%, and 13.5%, less than the Polyester, Luxous, and Tempa screens respectively. Thus, our experiments confirm that the use of multi-layered thermal screen can reduce greenhouse heat energy requirement. Furthermore, screen-control with outside solar radiation at an optimum setpoint of 60 W·m−2 significantly influences the greenhouse’s energy conservation capacity, as it exhibited 699.5 MJ · m−2, the least energy demand of all strategies tested. Moreover, the proposed model allows dynamic simulation of greenhouse systems and enables researchers and farmers to evaluate different screens and screen control strategies that suit their investment capabilities and local weather conditions.

Trends and prospects of soil heating under conditions of protected ground

Such vital processes in vegetable plants, like absorption of carbon dioxide (photosynthesis), water intake, absorption of nutrients from the soil, respiration, evaporation of water (transpiration), nutrients transfer from roots to leaves and fruits, as well as macronutrients transfer from leaves to roots, depend on the temperature regime. The research of technical and economic parameters of popular de-vices for heating of greenhouses allowed to define quite a number of operational disadvantages. A device for air heating of the soil in protected ground conditions, designed to increase yield and reduce the energy intensity of vegetable growing in the protected ground, is developed by the fellow workers of the FSBEI of Higher Education Pskov State University. The device consists of assembled segments, combined in a system, and a special fan heater with a low temperature range. The proposed device allows to ensure an intensive development of the root system of vegetable crops; to hasten the planting time of seeds or seedlings, and, consequently, to increase a fruiting period; to prevent death of plants associated with frost and diseases, caused by temperature changes; and to reduce the cost of heating of the protected ground.

Heating canarian greenhouse with a passive solar water–sleeve system: Effect on microclimate and tomato crop yield

Heating greenhouses is indispensable for plant development particularly in winter when air temperature is lower. In that sense, passive solar heating is a promising alternative compared to classic methods such as fossil fuels that are cost impacted and harmful to the environment.The current work is devoted to the study of the effect of a solar heating system using black plastic sleeves filled with water on the microclimate, tomato yield and the dynamic population of the tomato key pest, Tuta absoluta (Lepidoptera: Gelechiidae) in canarian greenhouses.The results show that the use of this heating system, improves the nighttime temperature inside the greenhouse by 3.1 °C and reduce by 10% the relative humidity compared to the control greenhouse. This microclimate improvement has a positive impact on the tomato production. It has increased by 35% compared to the control greenhouse. It was also noted that the presence of this heating system lead to a decrease in the development the population of T. absoluta in the heated greenhouse.Based on these results, the solar passive water–sleeve heating system can be an eco-friendly tool to prevent intensive use of fuel fossil and negative effect on the environment.

DYNAMIC MODELING OF MICRO-CLIMATE CONDITIONS OF A GREENHOUSE COUPLED WITH COAL FIRED HOT-AIR FURNACE

ABSTRACT In this study, a thermal analysis of a greenhouse heated with a coal-fired furnace was done. A greenhouse in the Mediterranean basin of Turkey was modeled. Energy and mass balances were derived to estimate the inside air temperature, humidity ratio and soil surface temperature, and the coal consumption rate. A dynamic approach was taken into account to define the time-dependent changes of the parameters in the greenhouse during the coldest period of the region, January and February. The main heat loss of the greenhouse occurs through the wall, ceiling and ground by convection and conduction. This heat loss is 63% of the total daily heat gains of the greenhouse for the coldest day. Furnaces were designed to maintain the greenhouse inside temperature approximately at 15ºC and averagely 200 kg coal was consumed per day. The maximum coal consumption amount was 480 kg for the coldest day. A meteorological data based solar radiation model was used, including dry-bulb temperature, relative humidity, wind speed and cloud cover. The effect of the cloud cover on greenhouse heating was investigated. For the coldest day, rather the sunrise was at 07:00 am, the furnaces were fired up to 10:00 am because of low solar radiation at that cloudy sky condition period. During the daytime, solar energy storage in the soil led to an increase in soil temperature. Approximately 1.5ºC-2ºC temperature difference on the soil surface was computed before and after the daytime. Finally, thermal characteristics of the furnace such as flue gas temperature and flow rate, furnace wall temperature, required amount of air for the combustion process were determined.

Direct wind heating greenhouse underground heating system

China’s three northern regions are rich in wind energy resources, with annual wind speeds of more than 3m/s reaching 5,000 hours. Traditional greenhouses use coal-fired heating, which has high pollution and low efficiency. Therefore, the system ingeniously combines wind and heating, and proposes a system that directly combines water agitation heating and greenhouse heating to realize the direct conversion of wind energy to thermal energy. The working principle of the system is: when the wind speed reaches the starting wind speed of the wind turbine, the wind turbine blade rotates to drive the stirring device, and the water in the stirring device is heated by the heat, and when the local table temperature is low, the water can be released, and the water is buried. The serpentine pipes in the greenhouse soil heat the soil, and the temperature in the greenhouse will also increase. At the same time, the temperature in the greenhouse is monitored by the temperature control system. If the temperature rises faster, the fluid flow is adjusted to reduce the heat release. Achieve intelligent regulation of greenhouse temperature to maintain its temperature in a suitable range. The system uses a wind-mixing device to use the abundant wind resources in the Sanbei area for greenhouse heating, thereby keeping the greenhouse temperature stable. From the perspective of green and energy saving, it has created an effective way to warm the greenhouse in winter. In the true sense, the consumption of fossil energy has been reduced, and the criteria for appropriate localization and recycling and renewable development have been realized.

Analysis of Heat Emission from Hot Water Pipe for Greenhouse Heating System Design

Analysis of Heat Emission from Hot Water Pipe for Greenhouse Heating System Design

CFD analysis of greenhouse heating using flue gas and hot water heat sink pipe networks

In this study, CFD analysis has been conducted and compared with already developed heat transfer model (HTM) to predict the heating load generated by (i) flue gas heat sink pipe network (FGHSPN) handling flue gas at 350 °C and (ii) hot water heat sink pipe network (HWHSPN) receiving hot water at 65 °C for accurately computing the heating requirements in order to determine the effect of each system on the greenhouse temperature rise. The heat was generated using innovatively designed forced draft paddy straw bale combustor (FDPSBC) through combustion of paddy straw biomass bales in single operation of FDPSBC which was coupled with a 100 m2 area greenhouse. The results of both CFD and HTM have been compared with the experimental results performed during winter night in Ludhiana city (30.56°N latitude, India). The heat released through radiation and free convection was computed through two methods viz; an unstructured mesh with 509,153 elements was used for simulation using CFD. The simulation was 3D pressure-based, transient analysis with activated energy, laminar viscous and surface to surface radiation models without taking into account the effect of incident solar radiation. Simulated results show that the total heat transfer by radiation and convection mode was 8.70 kW and 4.68 kW (total 13.38 kW) respectively resulting in steady-state greenhouse temperature rise of 10.35 °C above the ambient air. The CFD simulated results match with heat transfer model results of 12.98 kW (RMSE of 1.5%) and also comparable with experimentally observed temperature profile inside the greenhouse with RMSE of 1% which show the utility of CFD to study greenhouse microclimatic parameters and predict the heating load requirements without using complicated heat transfer equations and mathematical solutions.

Increasing heat creates hardship for brick kiln workers in Chennai, India and the alternative pathways reducing it

Climate change brings new burdens to people working outdoors. Migrant populations working at brick kilns in India are one such group facing dangerously overheated working conditions. Many migrate to the kilns from rural areas under bonded labor conditions. We argue that solutions need to go beyond industry-oriented technology-based solutions and focus on the social problem and take a people focused stance. In addition to adopting more locally appropriate technologies to reduce greenhouse gas emissions and heat in the work environment, solutions focusing on the workers situation must be considered from a human rights perspective.

Optimal processing of greenhouse crop residues to use as energy and CO2 sources

This work presents the development of suitable strategies focusing on greenhouse crop residues as energy and CO2 sources for improved food production in greenhouses. The utilization of greenhouse crop residues in combustion processes for heating and carbonic enrichment in greenhouses has previously been developed and evaluated. Nevertheless, greenhouse crop residues present several problems that make it difficult to use them for these purposes. Among the characteristics that can impede their use are excessive moisture and ash contents as well as their low density. In this work, the relevant solid fuel properties for this type of biomass have been studied.In addition, three pre-treatment strategies are proposed and evaluated, which aim to enhance the fuel quality of this biomass. These strategies were: 1) first relates to the drying strategy employed for reducing greenhouse crop residue moisture. 2) the second one relates to a reduction in ash content by avoiding contact with greenhouse soil and 3) mixing with other biomass kinds with better quality as solid fuels.The assays performed showed that these strategies were successful, resulting in biomass with a high heating value, up to 26.9 MJ/kg, and a lower ash content than untreated residues, with values as low as 13.0% dry weight. This value is closer to that for the standard biomass most commonly employed in direct combustion applications. The biomass produced has been verified as suitable for conventional boilers with thermal efficiencies up to 70%. The methods developed allow to reuse greenhouse crop residues as greenhouse fuel, providing both heat and CO2; thus enhancing production and sustainability.

Grid-Specific Co-Optimization of Incentive for Generation Planning in Power Systems With Renewable Energy Sources

Enhancement in efficiency of renewable energy sources, raised concern about greenhouse gas emission, significant power losses within transmission and distribution networks, unpredictable and unreliable fossil fuel cost, and expansion of reliable communication infrastructure offered by smart grids have all contributed to an increasing interest in deployment of renewable energy sources in energy mix. However, the widespread utilization of renewable energy sources in an open energy market without proper grid-based incentives for aimed contribution levels is uncertain. This article proposes a co-optimization algorithm to find the minimum incentives that result in the desired level of renewable energy source penetration in energy supply chain and optimal distribution of power sources in the electric power grid. The algorithm first finds the proper incentive based on the power-flow losses, then it uses a novel optimization approach to solve a mixed integer non-linear programming optimization of generation planning to minimize the energy cost. Unlike other incentive design methodologies, the proposed algorithm is not only supply specific, but also it depends on the demand and the structures of the grid. The method finds an exclusively designed set of incentives for electric energy supplies that do not emit greenhouse gases or heat to the atmosphere.

Edible Oils as Practical Phase Change Materials for Thermal Energy Storage

Edible oils could provide more accessible alternatives to other phase change materials (PCMs) for consumers who wish to build a thermal energy storage (TES) system with sustainable materials. Edible oils have good shelf life, can be acquired easily from local stores and can be less expensive than other PCMs. In this work, we explore whether margarine, vegetable shortening, and coconut oil are feasible PCMs, by investigations of their thermal properties and thermal stability. We found that margarine and vegetable shortening are not useful for TES due to their low latent heat of fusion, ΔfusH, and poor thermal stability. In contrast, coconut oil remained thermally stable after 200 melt-freeze cycles, and has a large ΔfusH of 105 ± 11 J g−1, a low degree of supercooling and a transition temperature, Tmpt = 24.5 ± 1.5 °C, that makes it very useful for TES in buildings. We also determined coconut oil’s heat capacity and thermal conductivity as functions of temperature and used the measured properties to evaluate the feasibility of coconut oil for thermal buffering and passive heating of a residential-scale greenhouse.