Application of an alternative energy source in the form of solar radiation and carbon-based fuel flexible material for the heating of mobile farm housing

Introduction

The microclimate of residential and industrial premises should provide optimal conditions for human life, contributes to the preservation of the internal balance of the human, maintaining his/her ability to work at the proper level (Iyendo et al., 2016).

The acceptable and recommended values of the microclimate, as well as the requirements for the design, installation and maintenance of heating systems are established by the current state standards. Residential heating systems, as well as other engineering communications must be designed and assembled to meet energy efficiency and safety requirements (Peculiarities of Installing Heating Systems in a Residential Building. Electronic Resource, 2020).

It still remains a challenge to develop highly efficient heating products with high heating rates and stable heat dissipation. In the course of the study, the research materials of some scientists were studied and the following information was identified.

Infrared radiation materials including tourmaline, ZrO₂, and medical stone nanoparticles (NPs) were successfully introduced into the carbon fabric through interfacial adhesion. It was found that 30% tourmaline, 9% ZrO₂, and 15% medical stone exhibited excellent heat generation performance among different samples with different ingredients. The temperature with degrees Celsius of heating fabric can be rapidly raised up from room temperature to around 60 °C in 10 min under a voltage of 10 V. This infrared heating element is expected to be widely applied in the fields of physiotherapy, biomedical treatment and flexible electronics (Tian et al., 2021).

A solar dryer comprised of a smooth solar air heater, shell and tube storage unit, and drying chamber, has been constructed and tested to dry a Chinese medicinal fungus (Poria Cocos). The dryer has been operated under two airflow rates and then, energy and exergy analysis applied to the system. The results show that: solar air heater averaged thermal and exergy efficiency were 66.2% (Abdelkader et al., 2021).

Owing to easy processability, ultralight weight, and low cost, carbon- and polymer-based composite materials are among emerging and promising electrothermal materials for high-performance flexible electric heaters. A sandwich-like structured electrothermal film composed of hybrid conductive fillers [Super-P (SP) and graphite], polymer blends matrix [thermoplastic polyurethane (TPU) and polyethersulfone (PES)], and alumina oxide (Al₂O₃) as a non-conductive filler has been fabricated by a facile slurry coating method Hybrid conductive fillers of graphite and SP particles have a uniform spatial distribution in a TPU/PES polymer matrix, which construct a highly stable and continuous conductive network with a low percolation threshold of conductive filler content that allows electrothermal films to operate at a low applied dc voltage (Xia et al., 2021).

In Iraq, a study to demonstrate the possibility of taking advantage of the high solar radiation effectively in heating the air for worming rooms and buildings in winter was conducted. The optimal diffusion of solar air heating applications depends mainly on the amount of heat stored and how quickly this heat is transferred to the air. The use of phase change materials to increase thermal storage is one of the best alternatives to date. The disadvantage of these materials is a clear reduction in their thermal conductivity, which impedes the rapid transfer of heat from them to the air. In this study, single wall carbon nanotubes (SWCNTs) was added to a local Iraqi made paraffin wax, and the nanocomposite was used in a solar air heater. The SWCNT/paraffin nanocomposite thermophysical pro-perties were examined to show its effect on the solar air heater performance. The SWCNT/paraffin nanocomposite has improved the stored thermal energy by 20.7% for natural convection, and by 21.2% for forced convection compared to pure paraffin. Results of practical tests confirmed the possibility of using the proposed air heater to work in Iraqi weather conditions (Habib et al., 2021).

An all printed flexible, energy-efficient heater was fabricated using a conductive ink principally made of MWCNT. Herein, a systematic investigation on employing PEDOT:PSS as an effective binder and dispersant for affordable conductive ink manufacturing was carried out. Screen printable room temperature curing formulation made of MWCNT and PEDOT:PSS is being reported for the first time. The ink’s enhanced stability is contributed by the π-π interaction between MWCNT and PEDOT:PSS. The screen printed flexible heater based on MWCNT-PEDOT:PSS nanocomposite has impressive energy efficiency and thermal stability, generating a peak temperature of 136 °C at the expense of only 0.137 W/cm² (Pillai et al., 2021).

Heat pump water heaters (HPWHs) could reduce residential energy consumption but there are two barriers preventing their uptake: the space cooling effect which increases space heating costs in cold climates and the high capital costs. These barriers may be mitigated by coupling a HPWH with an air-based solar collector to preheat inlet HPWH air, and using a lifecycle thinking approach to evaluate HPWHs or solar-assisted HPWHs (SAHPWHs) to encompass low operating costs. The findings presented illustrate economical clean water heating options, and subsidies that could be introduced to further encourage uptake of low carbon water heating (Treichel and Cruickshank, 2021).

A graphene-based film heater is proposed based on laser-reduced graphene oxide (LRGO) fabricated by the simple and eco-friendly laser direct writing technology at ambient conditions. Benefiting from high photothermal effect of CO₂ laser with wavelength of 10.6 um, the LRGO-based film heater has a high heating rate of 15.3 °C/s up to 196 °C with a fast response of 12.84 s at a low power density of 1 W/cm². Moreover, it exhibits good anti-interference ability to the mechanical effect and shows potential important application for de-icing. This work is helpful for the development of graphene-based device in practical application (Huang et al., 2021).

The uncertainties such as loads and renewable energy sources have significant impacts on operational performances of hybrid combined cooling, heating, and power (CCHP) systems. A multi-objective stochastic optimization model of a hybrid CCHP system is proposed, which contains a gas turbine, photovoltaic/thermal collectors, an absorption chiller/heater, a ground source heat pump, and storage devices of battery and water tank. Considering the uncertainties with system reliability, the hybrid CCHP system is optimized to achieve the best energetic, economic, and environmental benefits using the non-dominated sorting genetic algorithm-II (Wang et al., 2021).

An experimental study has been carried out to enhance a solar air heater’s performance by integrating artificial roughness through baffles on the absorber plate (Rajendran et al., 2021).

The leading study investigates the experimental development of a new energy-saving system by integrating a solar water heater and solar cooling absorption cycle with a conventional boiler for domestic hot water and heating purposes. A 65 flat plate solar collector-chiller system with a total surface area of 130 m² was integrated with the boiler and used to supply heating and cooling for a three-story building (1500 m²). The solar water heating/cooling system has the potential to provide more than 50% of the house energy demand free of charge with a significant reduction in carbon footprint (Al-Smairan et al., 2021).

Douglas Haigh analyzed the experience of heating rooms using solar collectors (panels) in some countries, found that the most optimal is to use them for indirect heating of water in the storage tank, which is then heated directly by an additional heating device (for example, a gas boiler) (Solar Thermal Systems. Electronic Resource, 2020).

Of great interest is the work “Solar energy for net zero energy buildings—a comparison between solar thermal, PV and photovoltaic–thermal (PV/T) systems”, in which comparative modeling of solar thermal, PV and photovoltaic systems has been carried out. The research has established that “… for local energy generation, solar thermal and photovoltaic (PV) installations will eventually compete for space on roofs and facades. Hybrid photovoltaic–thermal (PV/T) modules, in which heat and electricity is generated simultaneously, are therefore an interesting technology for building applications, which can potentially lead to a higher total efficiency and lower use of space.” (Good et al., 2015).

In areas without central heating, heating of mobile residential premises is provided by solid fuel boilers or stoves using firewood, coal, pellets, etc. Recently, pyrolysis furnaces of long-term combustion have been used. It is possible to use bioethanol as a source of electrical and thermal energy (Ismuratov et al., 2020).

In this case, gas and liquid fuel furnaces or boilers can be used. The most popular furnace in the Russian Federation is the Solarogas PO brand stove with a heat output of 1.8 kW. The main problems of diesel-fuelled heaters are:

• complicated ignition with the release of a large amount of carbon monoxide;

• unpleasant smell during the burner start-up;

• frequent replacement of the wick, cleaning of the burner.

Therefore, a liquid fuel furnace is usually started on the street, brought in after the combustion chamber has warmed up. The second option is a diesel heat gun with a torch burner. A fan heater is much more efficient than thermal panels, convectors, oil and water heating registers. Therefore, if necessary, for year-round operation, it is better to consider this heating option.

The disadvantage of a heat gun is energy dependence. In the absence of electricity, the fan will not work; the efficiency of the thermal device will decrease. There may be fuel outages at a distance from an inhabited locality (Heating a Cabin in Winter. Electronic Resource, 2016).

At remote sites, where the work cycle runs from April to November, wood-burning cookers remain almost the traditional way of heating systems. This includes distant livestock workers and field workers who are engaged in sowing or harvesting crops.

However, if there is a considerable distance (40–100km) from the settlement, there are problems with fuel supply:

• lack of road infrastructure;

• the delivery of firewood, coal, liquid or liquefied gaseous fuel is expensive;

• fuel storage requires the use of special rooms or containers, which reduces mobility;

• lack of centralized power supply.

Thus, the question about the use of alternative energy for heating mobile residential premises arises.

The climate of Kazakhstan is sharply continental in most of the territory, with large temperature amplitudes; relatively dry. In the northern regions of Kazakhstan, the West Siberian climatic region of a moderate climate prevails. Spring is short with a sharp temperature drop; it begins in mid-April and lasts on average about a month. In the summer, precipitation falls in the form of heavy rains, but in some years, most often in the northern parts of the region, precipitation can be prolonged. In summer, frosts are observed in June and August. Autumn is dry with early frosts. Despite the long cold period, the resources of solar radiation are high. The territory of Northern Kazakhstan extends in the range from 49°s. w. to 55° s. w. In this connection, there is a significant fluctuation of daylight depending on the time of year (Climate of Kazakhstan. Electronic Resource, 2021).

The objective of the current study is to investigate the use of an alternative energy source in the form of solar radiation and carbon-based fuel flexible material as a heater for the heating of farmers’ mobile houses.

Materials and Research Methodology

The research was carried out on the basis of the Kostanay Engineering and Economic University named after M. Dulatov and the limited liability partnership “Astyk Elevator Equipment Plant”. The “Astyk” elevator equipment plant has own production sites, uses high-quality domestic and imported materials and modern technologies. The plant produces elevator equipment, granaries and mobile houses for farmers. The farmer’s house is installed on the trailer chassis, which allows it to be transfered by trucks (Figures 1 and 2).

Figure 1:

Figure 2:

The farmer’s house is designed for use in various conditions with the possibility of mobile delivery to any area. The farmer’s house is very convenient to use in rural areas, for the conditions of “shift work”, etc. The house is equipped with a shower, a sink, a bio toilet, a bunk bed, a table for a gas stove and cooking, a wardrobe, a solid fuel stove, a photoelectric kit (solar battery, 100 W battery, 220 W lighting, a 3 kW gas generator). The windows of the house are plastic triple glazing with a complex opening. There is a shower tank with electric heaters and a service water tank. The equipment of the house can be completed according to the customer’s request - axe, hacksaw, shovel, jerrycan, blowtorch, paraffin lamp, bucket and other tools. The temperature conditions of the cabin allow it to be used in the temperature range from ‒50 to +50°C (Farmer’s house. Electronic resource, 2021).

Characteristics of the mobile farmer’s house (Fig. 2):

• height: 2.5 m;

• width: 2.4 m;

• length: 4.2 m;

• the walls are made of sandwich panels on a basalt basis, the wall thickness is 50 mm;

• plastic window 1000 × 800 mm with triple glazing;

• the floor is covered with a felt-based linoleum.

The authors have proposed a heating system for farmer’s house. The system heats mobile homes remote from power lines and settlements through the use carbon-based fuel flexible material and solar plants. The technical result consists in that, in the claimed system, the heating device is a carbon-based fuel flexible material supplying electricity from the solar station.

Carbon-based fuel flexible material is a thermal film (heating grid), which is made by interweaving longitudinal and transverse carbon filaments and, for safety reasons, covered with an electrical insulating material.

The heat source in the mesh is a heating carbon filament with a conductive layer without the use of metal (Pat. Nº-17940, KZ; Kogay et al., 2015). The heating elements are laminated on both sides in special electro technical polyester that provides full water resistance and high protection from electrical puncture. The film can therefore be used for both supplementary and primary space heating by installing in wall panels, ceilings and floors.

1—Trailer chassis (new) 2PTS-6.5; 2—Plastic window (1000  ×  800)  mm (difficult opening); 3—Plastic window (800  ×  500) mm (difficult opening); 4—Plastic window (500  ×  500) mm (with opening); 5—Entrance door (metal insulated with a mortise lock) (1900  ×  800)  mm; 6—Ladder ladder with handrail (1200  ×  800)  mm; 7—Removable ladder (2850  ×  434)  mm (telescopic); 8—Box 3-section (1100 × 500 × 500)  mm; 9—Inventory box (2300 × 1100 × 500)  mm; 10—Front door light.

Interior layout

At the same time, the heater is not designed for outdoor use without proper protection. The product is manufactured using a polymer film (polyester) with high dielectric values; it conducts infrared heat well and is heat resistant. The carbon paste is applied to the polymer film with a technological precision of less than 1 micron. The process of applying the carbon and other materials and the final lamination itself takes place at 140 °C (Figures 3 and 4).

Figure 3:

Figure 4:

Carbon fiber is characterized by high strength, wear resistance, rigidity and low weight compared to steel. Its density ranges from 1450 to 2000 kg/m³.

The higher price of carbon fiber compared to fiberglass plastic and glass fiber is due to the more complex, energy-intensive, multi-step process, expensive resins and more expensive equipment. Moreover the strength and elasticity are higher, in addition to a number of other undisputed benefits:

1. 40% lighter than steel and 20% lighter than aluminum;

2. carbon made from carbon is slightly heavier than from carbon and rubber, but much stronger; it cracks and crumbles on impact, but does not shatter;

3. high temperature resistance: carbon retains its shape and properties up to +200°C;

4. has good vibration absorbing properties and thermal capacity;

5. corrosion resistance;

6. high tensile strength and elastic limit;

7. aesthetic and decorative features.

Solar plant includes two monocrystalline solar modules ZDNY-250C60 sized 1650 × 992 × 45 mm with capacity 250 W, PWM controller, sinusoidal inverter IS-24-1500U, two storage batteries with capacity 100 A*hour.

The structure of the ZDNY-250C60 (Table 1) monocrystalline solar module consists of many silicon cells that convert sunlight into electricity (Fig. 5). The advantages of these panels are the compactness, low weight and higher efficiency. The monocrystalline panels are placed in a robust and sturdy fiberglass enclosure that protects the photovoltaic cell from moisture and dust penetration.

Table 1.

Technical characteristics of the ZDNY-250C60 monocrystalline solar module.

Figure 5:

The heating system works as follows. The electric current from the two batteries is supplied to the inverter, which converts the direct current into alternating current and changes the voltage from 24 to 220 V.

Then the current from the inverter is delivered to the heater with the carbon-based fuel material. To regulate the temperature of the carbon heater, a thermostat is installed between the inverter and the heater, which regulates the temperature of the carbon-based fuel material installed in the heater. During operation, the batteries are charged from the two solar panels via the controller.

In order to conduct research on the application of a mobile residential heating system using solar panels and carbon-based flexible fuel material, a solar station and a heater with carbon-based flexible fuel material were installed on the farmer’s mobile house (Figure 6A, B). Previously, a solar panel was installed on the house to power the light (on Figure 6A near the window).

Figure 6:

Inclination angle of solar panels is 55°.

In the course of the research, natural light was measured on different days and hours using the luxmeter “TKA-Lux”, the current flow to the heater using the M266 current clamp, outdoor temperature, indoor temperature, battery condition using the discharge tester, and the temperature produced by the carbon heater using the Testo 875 thermal imager.

The research was carried out in an unheated room.

The heating system was then installed in a stationary heated room of 46.2 m² (Figure 7).

Figure 7:

Research results

Research on the operation of the heating system installed in the farmer’s house was conducted in February 2021. During the operation of this heating system in winter conditions, the value of daylight illumination varied from 20  ×  10³ to 94  ×  10³ lx, depending on the time of day on sunny days (see Figure 8).

Figure 8:

Most of February in Kostanay was overcast, but there were sunny and cloudy days. 14% were sunny days, 24% cloudy days, 62% overcast days (Weather in Kostanay in February. Electronic Resource, 2021).

The highest daytime temperature in February 2021 was 1°C. While the minimum night-time temperature dropped to minus 29°C. The average daytime and night-time temperatures during February were minus 13.5°C and minus 15.6°C, respectively.

The average wind speed in February was 4.2 m/s.

The average daily sunshine in Kostanay in February was 3.2 hr.

During operation, the heater consumed an average of 523 watts of energy (Fig. 9), the maximum heating temperature was 68°C, when the room temperature changed from ‒11°C to +8°C (Fig. 10).

Figure 9:

Figure 10:

On average, the charge of two batteries, each with a capacity of 100 A*hour, was enough for an estimated of 3 hr, after which the heaters stopped working. Due to the low temperature inside the room, battery charge losses occurred.

During the operation of the heating system in a stationary heated room with an area of 46.2 m² in March–April 2021, the following results were obtained.

The average illumination of the daylight ranged from 36,840 to 103,350 lx (Figure 11).

Figure 11:

The fluctuation of the ambient temperature depending on the time of day is shown in Figure 12.

Figure 12:

The average energy consumption was 531W. The maximum heating temperature of the carbon-based fuel flexible material heater was 68°C. A maximum charge of 150 A*hour batteries was sufficient for 6 hr.

Discussion

The conducted studies have shown that:

1. The proposed residential heating system is functional;

2. The power of solar panels of 250 W and the number of batteries is not sufficient for long-term operation of a heater with a carbon-based fuel flexible material;

3. For the normal operation of the batteries inside the room, it is necessary to ensure the temperature according to the operating requirements. At low temperatures, there is a rapid discharge and a decrease in capacity. Low temperatures affect different types of lead-acid batteries in different ways, but they have an equally bad effect on the operation and characteristics of the battery. The electrolyte freezes and crystallizes, which can damage the battery banks and the spongy material of the plates. On average, the influence of temperatures is as follows: from 0°C to ‒10°C, the charging and discharge characteristics decrease, which slightly affect the operation; from ‒10°C to ‒20°C, in the starter mode, the current decreases and the charge worsens; at a temperature below ‒15°C, the gas recombination mechanism inside the sealed lead battery stops working, and the electrolyte loses water. Based on the above data, we can conclude that the low temperature for high-quality operation of a lead-acid battery starts somewhere from ‒10°C to ‒15°C;

4. In the conditions of northern Kazakhstan, the daylight duration in winter is short with a large number of cloudy days and the panels cannot generate enough energy. Therefore, there is a need to increase the number of solar panels and batteries for long-term operation of the heater;

5. In winter conditions (when the temperature is below 15°C), the applicability of this room heating system is not possible or it is possible as an additional system, but not as the main heating system;

6. Basically, this heating system is applicable in the autumn-spring period for heating rooms of a small area. In autumn and spring, there is a long daylight period, with more sunny days.

In comparison with the above-mentioned systems, the proposed system with a solar station and a heater with a carbon-based fuel flexible material does not contain stone nanoparticles, paraffin wax, conductive ink and has no air blowing. The advantage of a heater with a carbon-based fuel flexible material is the use of a heating carbon filament with a polymer film, which perfectly conducts infrared heat. Technical characteristics of a heater with a carbon-based fuel flexible material: power consumption when heated at 60°C - 115 W/m²; the current flowing through one thread is not more than 5 mA; heat transfer 1 kW–12,000 kcal.

From research by other scientists, it has been established that:

1. Heating your home with an active solar energy system can significantly reduce your fuel bills in the winter. A solar heating system will also reduce the amount of air pollution and greenhouse gases that result from your use of fossil fuels for heating or generating the electricity (Active Solar Heating. Electronic Resource, 2020).

2. Solar air heaters are not as commonly available as conventional space heaters (yet), but they are beginning to catch on in popularity due to how incredibly energy efficient they are, especially when compared to even the most energy efficient conventional space heaters. Keeping that in mind, the following are some of the different companies that manufacture some of the best solar air heaters currently on the market: Grammer Solar, which are built using aluminum air collectors and insulated pipes through which the heat is channeled into the house; Solar Infra Systems, which has a portable solar air heater; Sunfire solar air heaters are build using aluminum and tempered glass (What is the most energy efficient space heater—and the best solar air heater? Electronic Resource, 2020).

3. It is recommended to use solar photovoltaic panels rather than solar air and water heaters. Better to install more PV panels and use an efficient electric heater (Why We No Longer Sell Solar Air Heaters. Electronic Resource, 2019).

From the above it follows that it is necessary to search for an effective heater operating on electric energy with a small consumption of it; the generation of electric energy must be provided from solar panels.

Conclusion

Studies have shown that there is a need to develop solar heating systems. The use of carbon as a fuel element in various industries confirms significant energy savings, environmental improvements and lower operating costs. The special climatic conditions of Kazakhstan, the increasing volumes of solid fuel consumption for heating and hot water supply make it necessary to comprehensively develop solar energy. The use of solar energy is all the more justified for objects cut off from centralized heat and power supply systems: small villages and auls, farmer formations, and pasture cattle breeding. In our case, we consider the option of using a carbon heater complete with a solar battery, as one of the main elements for generating electrical energy and heat-generating material. Carbonates include all composite materials in which carbon fibers are the supporting base, and the binder can be different. It should be emphasized that carbon is an innovative material. The flexibility of the carbon cloth, the possibility of convenient cutting, followed by impregnation with epoxy resin, make it possible to form carbon products of any shape and size. The resulting blanks can be grinded, polished, painted and flexo printed. The popularity of carbon fiber reinforced plastic (carbon fiber) is explained by its unique performance characteristics obtained as a result of combining materials that are completely different in their properties in one composite.

According to the conducted studies, for further research it is recommended to equip the farmer’s mobile house with 400 W solar panels in the amount of 4 pieces, batteries with a capacity of 120 A*h in the amount of 4 pieces and one heater made carbon-based fuel flexible material. Also, the heating system must be equipped with a “day-night” sensor. This sensor will allow us to turn off the heater at night. It is necessary to install a battery heating system, which provides a normal temperature regime for the operation of the batteries. In order for the indoor microclimate to be physiologically favorable for human, it becomes necessary to install a humidity control system.

Acknowledgments

The research is funded by the Science Committee of the Ministry of Education and Science of the Republic of Kazakhstan (Grant No. AP08956558).

Indicator name	Value
Maximum power, Pmax	250 W
Voltage at Pmax, Vm	31.17 V
Current at Pmax, Im	8.03A
Open circuit voltage. Voc	37.85V
Short circuit type, Isc	8.40A
Cell efficiency	17.4%
Panel efficiency	15.3%
Cell type	Monocrystal, 156 × 156 mm
Power deviation (Pmax)	+0–3%
Number of cells	60
Panel size, mm	1650 × 992 × 45
Weight, kg	22.5
Maximum system voltage	1000V(TUV)/600V(UL)
Maximum fuse current	15 A
Operating temperature	‒40 to 85°C
Nominal operating cell temperature	47°C
Temperature coefficient of Isc	+0.06%/°C
Temperature coefficient of Voc	‒0.35%/°C
Temperature coefficient of Pmax	‒0.4%/°C