Description:FIELD OF THE INVENTION
This invention relates to Green solar dryer with thermal storage towards reduction in pollution
BACKGROUND OF THE INVENTION
Conventional dryers operate at medium temperatures using fossil fuels, contributing to greenhouse gas emissions and environmental pollution. Indirect drying, commonly used in industries, also relies on fossil fuels, further exacerbating these concerns. In small-scale industries, pulse dryers are widely used and are powered by electricity, liquefied petroleum gas (LPG), or diesel. These energy sources generate significant greenhouse gases, making them unsustainable in the long run. The continuous batch dryers operating on electricity, LPG, and diesel fuel are particularly concerning due to their energy-intensive nature and reliance on non-renewable resources. To address this issue, solar drying has emerged as a viable and environmentally friendly alternative. Among various solar drying technologies, a renewable energy assisted drying approach, combined with a high-temperature thermal energy storage system, presents a promising innovation. This method utilizes concentrated solar power (CSP) to provide a stable and efficient heat source for drying applications. By replacing conventional fossil fuel-based grain dryers in small-scale industries with solar-powered indirect drying systems, it is possible to significantly reduce greenhouse gas emissions, enhance energy efficiency, and lower operational costs. The integration of a thermal energy storage system ensures a consistent energy supply, overcoming the intermittent nature of solar radiation. This approach not only contributes to sustainable industrial practices but also aligns with global efforts to mitigate climate change and promote renewable energy adoption. As industries seek greener alternatives, solar-based indirect drying offers a practical and cost-effective solution, making it a crucial advancement for sustainable drying technology.
US10470474B2 Grain dryer of the type comprising a vertical main structure consisting of a central body through which the grain to be dried passes, a front hot air intake chamber and a rear used air outlet chamber, being that the main body has in its upper part an entrance from where wet grains are loaded, underneath which there is a loading hopper that communicates with the central body, wherein the grain descends along the central body within which it is dried during its fall by a flow of hot air that passes through the mass of grain, finally exiting through a discharge hopper arranged at the lower end of the dryer, the dryer of the invention being characterized in that it allows to significantly reduce the energy consumption in order to obtain a better quality of grain and a process much faster than conventional ones due to the arrangement of one or more preheating chambers without extraction of moisture from the grain.
RESEARCH GAP:
• Integration of TES ensures consistent operation, improving overall efficiency

• The optimized energy transfer reduces drying time compared to traditional fossil-fuel-based dryers.

• Uniform airflow ensures even moisture removal from grains.
US7818894B2 This process embodies forcing air through grain and granular biological products using a high-volume horizontal airflow from a central vertical pervious tube to one or more plenum chambers near the structure sidewall to dry or cool products. Cross-flow air movement can be supplied by either suction or pressure. This conditioning and drying method has advantages over conventional storage structures, especially where product depth is much greater than diameter. In this process, horizontal air typically moves only ? to ? of vertical distances. Horizontal airflow resistance through elongated seeds is 50-60 percent of vertical airflow. Power for horizontal airflow is typically 8-15% that of vertical airflow. Grain and seed drying costs will be 15-30% of high temperature drying. To enhance germination, storage and grain and seed quality, and to kill or exclude insect pests, ozone is applied to drying or aeration airstreams for treating stored products and storages.
RESEARCH GAP:
• No direct fossil fuel usage, reducing carbon emissions and greenhouse gas production.
• Suitable for various grain types and small-scale industries.
IN2015MU03384A This invention relates to CYLINDERICAL TYPE VERTICAL CONTINUOUS SI'.KD DRYER seed dryer which is useful in smaller and larger segment of the oil mill other grain industries and cottonseed related industries. The process is continuous and uninterrupted at a comparatively low investment cost compared to the other online dryers, for small segments of the industry and industries having limited period drying requirement in the season and especially for existing units with small areas for expansion. This invention suggests certain improvements over the past installations for general seed drying to eliminate manual handling and to obtain uniform drying. The cased screw conveyor provided over the apparatus supplies the seed in to the apparatus at center point with provision of excess material to be redirected back to supply point for recycling. Improvements have been done in the apparatus by provision of heating and cooling zone for better results. Particular improvements have been done to use it especially for cottonseed. Improvements have been done especially for cottonseed considering the fuzzy. heterogeneous properties and poor conductivity. The air quantity supply derivations, heat requirements, and retention time are derived for the cottonseed considering its typical nature for the desired output for industrial application.
RESEARCH GAP:
• The system utilizes solar energy as the primary heat source, reducing dependency on fossil fuels.
• Sustainable and renewable energy solution for grain drying.
• Can be scaled up for larger drying operations.
None of the prior art indicate above either alone or in combination with one another disclose what the present invention has disclosed. This invention relates to Green solar dryer with thermal storage towards reduction in pollution.
SUMMARY OF THE INVENTION
This summary is provided to introduce a selection of concepts, in a simplified format, that are further described in the detailed description of the invention.
This summary is neither intended to identify key or essential inventive concepts of the invention and nor is it intended for determining the scope of the invention.
To further clarify advantages and features of the present invention, a more particular description of the invention will be rendered by reference to specific embodiments thereof, which is illustrated in the appended drawings. It is appreciated that these drawings depict only typical embodiments of the invention and are therefore not to be considered limiting of its scope. The invention will be described and explained with additional specificity and detail with the accompanying drawings.
Thermal energy storage is useful when – (i) A gap between demand and supply of energy, (ii) Availability of energy is variable, (iii) Sources of energy are variable, (iv) Energy supply is limited, (v) Supply/load patterns are cyclic in nature, (vi) Demand loads are varying with time and, (vii) Energy cost is time dependent. The pulses dryer commercially used at small scale operates on electricity, LPG, and diesel, which produces greenhouse gases that cause environmental contamination and are a subject of concern. The solar dryer is one of their most efficient and profitable replacements. This innovation focuses on replacing commercially used grain dryers in small-scale industries with a novel solar drying approach combined with a high-temperature thermal energy storage system using concentrated solar power. Firstly, we have conducted a comprehensive review of concentrated solar thermal cooking technologies has been conducted, assessing their social, economic, and environmental impact across different climatic zones in developing countries like India. After that classification and comparison of different solar cooking technologies have been conducted, highlighting their advantages and limitations across various scenarios. The challenges and future directions for solar drying technologies have been identified through the survey. An industrial survey was conducted to collect essential parameters of continuous batch dryers operating on electricity, LPG, and diesel fuel. These parameters were then compared with those of a dryer integrated with thermal storage to evaluate the economic benefits of the solar drying unit. The critical parameters required to compare the performance of the dryers operating at different energy sources are evaluated. The drying system operates with inlet air heated to elevated temperatures under controlled static pressure conditions, enabling efficient moisture reduction within a specified drying duration. The system is capable of reducing the moisture content of agricultural products from higher levels to significantly lower levels within an optimized cycle time.
BRIEF DESCRIPTION OF THE DRAWINGS
The illustrated embodiments of the subject matter will be understood by reference to the drawings, wherein like parts are designated by like numerals throughout. The following description is intended only by way of example, and simply illustrates certain selected embodiments of devices, systems, and methods that are consistent with the subject matter as claimed herein, wherein:
Fig 1. Proposed components of solar drying unit
The figures depict embodiments of the present subject matter for the purposes of illustration only. A person skilled in the art will easily recognize from the following description that alternative embodiments of the structures and methods illustrated herein may be employed without departing from the principles of the disclosure described herein.
DETAILED DESCRIPTION OF THE INVENTION
The detailed description of various exemplary embodiments of the disclosure is described herein with reference to the accompanying drawings. It should be noted that the embodiments are described herein in such details as to clearly communicate the disclosure. However, the amount of details provided herein is not intended to limit the anticipated variations of embodiments; on the contrary, the intention is to cover all modifications, equivalents, and alternatives falling within the scope of the present disclosure as defined by the appended claims.
It is also to be understood that various arrangements may be devised that, although not explicitly described or shown herein, embody the principles of the present disclosure. Moreover, all statements herein reciting principles, aspects, and embodiments of the present disclosure, as well as specific examples, are intended to encompass equivalents thereof.
The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of example embodiments. As used herein, the singular forms “a",” “an” and “the” are intended to include the plural forms as well, unless the context clearly indicates otherwise. It will be further understood that the terms “comprises,” “comprising,” “includes” and/or “including,” when used herein, specify the presence of stated features, integers, steps, operations, elements and/or components, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components and/or groups thereof.
It should also be noted that in some alternative implementations, the functions/acts noted may occur out of the order noted in the figures. For example, two figures shown in succession may, in fact, be executed concurrently or may sometimes be executed in the reverse order, depending upon the functionality/acts involved.
In addition, the descriptions of "first", "second", “third”, and the like in the present invention are used for the purpose of description only, and are not to be construed as indicating or implying their relative importance or implicitly indicating the number of technical features indicated. Thus, features defining "first" and "second" may include at least one of the features, either explicitly or implicitly.
Unless otherwise defined, all terms (including technical and scientific terms) used herein have the same meaning as commonly understood by one of ordinary skill in the art to which example embodiments belong. It will be further understood that terms, e.g., those defined in commonly used dictionaries, should be interpreted as having a meaning that is consistent with their meaning in the context of the relevant art and will not be interpreted in an idealized or overly formal sense unless expressly so defined herein.
Thermal energy storage is useful when – (i) A gap between demand and supply of energy, (ii) Availability of energy is variable, (iii) Sources of energy are variable, (iv) Energy supply is limited, (v) Supply/load patterns are cyclic in nature, (vi) Demand loads are varying with time and, (vii) Energy cost is time dependent. The pulses dryer commercially used at small scale operates on electricity, LPG, and diesel, which produces greenhouse gases that cause environmental contamination and are a subject of concern. The solar dryer is one of their most efficient and profitable replacements. This innovation focuses on replacing commercially used grain dryers in small-scale industries with a novel solar drying approach combined with a high-temperature thermal energy storage system using concentrated solar power. Firstly, we have conducted a comprehensive review of concentrated solar thermal cooking technologies has been conducted, assessing their social, economic, and environmental impact across different climatic zones in developing countries like India. After that classification and comparison of different solar cooking technologies have been conducted, highlighting their advantages and limitations across various scenarios. The challenges and future directions for solar drying technologies have been identified through the survey. An industrial survey was conducted to collect essential parameters of continuous batch dryers operating on electricity, LPG, and diesel fuel. These parameters were then compared with those of a dryer integrated with thermal storage to evaluate the economic benefits of the solar drying unit. The critical parameters required to compare the performance of the dryers operating at different energy sources are evaluated. The drying system operates with inlet air heated to elevated temperatures under controlled static pressure conditions, enabling efficient moisture reduction within a specified drying duration. The system is capable of reducing the moisture content of agricultural products from higher levels to significantly lower levels within an optimized cycle time. The energy consumption profile may vary depending on the batch size, with increased input loads leading to proportional adjustments in electricity, LPG, or diesel usage. However, the dryer maintains improved energy efficiency with scalable capacity. Suitable materials for construction of the trays and drying chamber include corrosion-resistant metals such as aluminium and stainless-steel variants (e.g., SS304, SS316), selected based on durability, thermal stability, and hygiene standards. The tray dimensions and cabinet configurations can be modified as per application-specific requirements. Based on experimental and field survey findings, a newly designed solar-assisted dryer incorporates a radiator-type heat exchanger to ensure uniform hot air distribution within the drying chamber. The drying chamber temperature can be maintained at elevated levels, and both temperature and humidity are modulated using a precision control system to accommodate the drying characteristics of various crops or food products. For economic evaluation, the system has been compared with conventional dryers powered by electricity, LPG, and diesel. In systems integrated with latent heat thermal energy storage (LHTES), notable operational cost savings have been observed. The estimated payback period varies depending on initial technology cost, regional climatic conditions, and policy incentives or subsidies, typically falling within a range suitable for commercial adoption. The proposed solar drying unit (SDU), integrated with a latent heat thermal energy storage (LHTES) system, is designed to efficiently dry agricultural materials such as grains. The system supports modular capacity and can accommodate varying input loads while maintaining high thermal efficiency and reducing dependency on fossil fuels. This technology offers substantial societal, economic, and environmental benefits by reducing emissions, lowering operating costs, and enhancing product quality. This system ensures continuous drying by storing solar energy in Thermal Energy Storage (TES), enabling drying operations even during periods of low solar radiation. The integration of TES helps in maintaining a consistent temperature, optimizing energy use, and improving overall drying efficiency. The system is structured to optimize the drying process by utilizing a solar collector, a heat transfer fluid (HTF), a radiator-type heat exchanger, and an air blower, ensuring uniform and effective moisture removal from the grains.
2. System Components and Their Functions
The schematic diagram (Fig 1) illustrates the key components of the proposed SDU, which include:
2.1. Solar Collector and Receiver
• The system is equipped with a solar concentrator dish, designed to capture and concentrate solar radiation for thermal energy generation.
• The concentrated solar energy is transferred to the HTF as it passes through a solar receiver.
• The receiver ensures effective absorption of solar heat and subsequent transfer to the radiator heat exchanger and TES unit.
• In the absence/non-availability of solar collector and receiver, heat can be obtained by using other mechanisms.
2.2. Thermal Energy Storage (TES) System
• Latent Heat Thermal Energy Storage (LHTES) is integrated into the drying system.
• The TES stores excess heat energy for later use, ensuring continuous operation even when solar radiation is insufficient.
• The TES unit is independent and functions by absorbing and releasing stored heat when needed.
Various researchers suggest solar drying solutions with thermal energy storage fused inside the drying chamber using PCM in melting temperature 50-60°C. The long-term substitute for commercially used electric and diesel dryers using solar power remains unresolved for commercialization and mass deployment. The investigations on high-temperature PCM in the TES technology are still untapped and call for more research. However, the novel technique described in this study proposes a high-temperature PCM-based TES and the design of a indirect dryer with front-mounted radiator-type heat exchanger to achieve the required temperature increase in ambient air temperature. This solar drying method, designed primarily for grain and pulse drying, is a commercially feasible drying technology. The current study proposes an independent TES system with CSP technology for the solar dryer. There are five possible operating strategy modes to meet the heat load with thermal storage system (i) Charging Mode (ii) Discharging Mode (iii) Discharge and Direct generation (iv) Charge and Direct Generation and (v) Direct generation

2.3. Heat Transfer Mechanism
• A heat transfer fluid (HTF), is used to transport thermal energy from the solar receiver to the heat exchanger and thermal energy storage (TES) unit.
• Heat distribution within the system is managed through strategically placed control valves, allowing redirection and modulation of thermal flow as needed.
• The HTF circulates through a closed-loop circuit using a dedicated pump, ensuring continuous and efficient heat exchange between system components.
2.4. Heat Exchanger
• The system includes a radiator-type heat exchanger designed to facilitate the transfer of thermal energy from the HTF to ambient air.
• Heated air generated through this process is directed into the drying chamber, where it aids in the controlled removal of moisture from agricultural materials or other drying substrates.
2.5. Air Blower System
• An air blower is employed to draw ambient air into the system and channel it through the heat exchanger.
• As the air passes through the exchanger, it is heated to a suitable drying temperature before entering the drying chamber.
• The heated airflow is distributed across perforated trays or drying surfaces, promoting uniform thermal exposure and effective moisture evaporation from the product being dried.

3. Energy Flow and Mass Flow Rate at Different State Points
The energy and mass flow rates at different state points in the drying unit provide insights into the system's efficiency.
3.1. Solar Energy Absorption
• A solar concentrator captures incident solar radiation and transfers the absorbed thermal energy to a circulating heat transfer fluid (HTF).
• The thermal energy collected varies depending on solar intensity and system configuration.
• The system is designed for high thermal efficiency to maximize the conversion of solar radiation into usable heat, ensuring optimal energy utilization under varying environmental conditions.
• Heat energy/power can also be received from other sources too.
3.2. Heat Transfer to the Dryer
• The HTF transfers heat to the drying air via a radiator-type heat exchanger.
• Excess thermal energy not immediately used for drying is diverted to a thermal energy storage (TES) unit for later use, particularly during periods of reduced solar availability.
• The flow of thermal energy between components is managed through a system of control valves that regulate heat delivery and storage operations.
3.3. Thermal Energy Storage Process
• During operation, surplus heat is directed to the TES unit where it is stored in the form of latent or sensible heat.
• The HTF exiting the TES unit is blended with the return stream from the heat exchanger to maintain a consistent supply temperature before being circulated back to the solar collector.
3.4. Airflow and Drying Process
• Ambient air enters the system and is passed through the heat exchanger, where it is heated to a temperature suitable for drying.
• The heated air is then introduced into the drying chamber, flowing through perforated trays or plates to ensure uniform heat distribution.
• As the air comes in contact with the product, it absorbs moisture, which is carried out of the system in the exhaust airflow.
4. System Operation and Performance
The system is designed for continuous operation, ensuring uninterrupted drying cycles by integrating the LHTES system.
• The thermal energy storage (TES) unit is designed to store excess heat during peak solar availability and release it as needed, ensuring consistent drying temperatures irrespective of solar fluctuations.
• A circulation pump drives the heat transfer fluid (HTF) through a closed-loop system, enabling continuous and efficient thermal energy transfer between components.
• An air blower operates in an open-loop configuration, drawing in ambient air and directing it through the heat exchanger to maintain optimal drying conditions within the chamber.
The proposed solar drying unit (SDU), integrated with a latent heat thermal energy storage (LHTES) system, provides a sustainable and energy-efficient solution for drying agricultural products. By utilizing solar energy as the primary heat source and storing surplus thermal energy for later use, the system enables continuous drying operations, even during periods of low or fluctuating solar radiation. The drying system comprises a solar concentrator, a heat transfer fluid (HTF) loop, a radiator-type heat exchanger, and a temperature-controlled drying chamber. This integrated design enhances thermal efficiency and minimizes environmental impact by reducing dependence on conventional fossil fuels. The system maintains a consistent drying environment by regulating air temperature and humidity, thereby facilitating uniform moisture removal from the product. Thermal energy is circulated through a closed-loop HTF system, while ambient air is supplied via an independent blower operating in an open-loop configuration. This setup ensures uniform airflow and effective heat transfer across the drying chamber. Overall, the solar-assisted drying system offers a clean and reliable alternative to conventional dryers, supporting energy conservation and environmental sustainability—particularly in small- to medium-scale agricultural operations.
ADVANTAGES OF THE INVENTION:
• The system utilizes solar energy as the primary heat source, reducing dependency on fossil fuels. Integration of TES ensures consistent operation, improving overall efficiency.
• The optimized energy transfer reduces drying time compared to traditional fossil-fuel-based dryers. Uniform airflow ensures even moisture removal from grains.
• No direct fossil fuel usage, reducing carbon emissions and greenhouse gas production. Sustainable and renewable energy solution for grain drying.
• Can be scaled up for larger drying operations. Suitable for various grain types and small-scale industries.
, Claims:1. A green solar dryer system with thermal energy storage, comprising:
a solar concentrator dish; a solar receiver;
a heat transfer fluid (HTF) circuit;
a radiator-type heat exchanger; a thermal energy storage (TES) unit;
a circulation pump;
an air blower; and
a drying chamber, wherein said system utilizes solar radiation to generate and store thermal energy for continuous drying operations with reduced environmental pollution.
2. The system as claimed in claim 1, wherein the solar concentrator dish is adapted to focus incident solar radiation onto the solar receiver, which in turn transfers the thermal energy to the HTF circulating through a closed-loop circuit.
3. The system as claimed in claim 1, wherein the TES unit comprises a latent heat thermal energy storage (LHTES) system utilizing phase change material (PCM) having a melting temperature range of 50°C to 60°C to store excess thermal energy during high solar intensity periods and release it during low or no solar radiation conditions.
4. The system as claimed in claim 1, wherein the radiator-type heat exchanger receives heated HTF and transfers the thermal energy to ambient air, which is then used for drying agricultural products placed within a temperature-controlled drying chamber.
5. The system as claimed in claim 1, wherein the HTF circulates between the solar receiver, heat exchanger, and TES unit via a pump-operated closed-loop circuit, enabling efficient and continuous thermal energy transfer.
6. The system as claimed in claim 1, wherein the air blower operates in an open-loop configuration to draw ambient air, pass it through the heat exchanger for heating, and deliver the heated air into the drying chamber through perforated trays to achieve uniform moisture removal.
7. The system as claimed in claim 1, wherein a plurality of control valves are integrated in the HTF circuit to regulate thermal energy flow, allowing multiple operational strategies including: (i) charging mode, (ii) discharging mode, (iii) direct generation mode, (iv) charge and direct generation mode, and (v) discharge and direct generation mode.
8. The system as claimed in claim 1, wherein the TES unit is configured to function independently, absorbing and releasing thermal energy as required, ensuring uninterrupted drying cycles regardless of solar availability.
9. The system as claimed in claim 1, wherein the drying system is adapted for agricultural products such as grains and pulses and provides a sustainable, commercially feasible alternative to conventional electric and diesel dryers
10. The system as claimed in claim 1, wherein the system is further operable by alternate heat sources in the absence of solar energy, enabling flexible deployment across different climatic or operational conditions.