# Promising Approaches for Heat Utilization in Agricultural Machinery Engines
## 2 Presentation of the Main Material
### Research Results  
There are two main schemes for the utilization of secondary energy resources: conventional and deep. For a long time, they have been developed mainly for ships and stationary power plants. The system of deep heat utilization (SDHU) provides consumers only with thermal energy. The system of deep utilization of heat (SDUH) is designed to provide consumers with thermal and mechanical/electrical energy. Water or liquids with a low boiling point (e.g., refrigerants) can be used as the working fluid [5]. The advantage of SDUH is its more efficient use of heat; its disadvantage is the complexity of the design, high initial cost and high operating cost. It is also more sensitive to changes in engine operating mode [6; 7]. The following methods of heat utilization are widely used today. In energy systems of mobile energy vehicles with frequent stops, especially cars, the efficiency of recycling systems can be increased by using heat accumulators. This can significantly reduce fuel consumption for engine heating, especially in the winter [8; 9; 10; 11]. The most common schemes that allow only partial utilization of spent thermal energy are cabin heating and fuel heating (when using gaseous fuel or highly viscous components). More complex engineering solutions are also used. For example, engineer [PERSON] proposed a six-stroke engine for heat recovery. He used water injection into the engine cylinders after the fourth stroke. The water is supplied at a pressure of up to 15 MPa, which evaporates and performs the working stroke. This allows the power of the engine to be increased by up to 40%, which leads to improvements in its economic and environmental indicators [12]. For a long time (since the 1980s), recycling thermoelectric generators (TEG) were considered promising. However, their widespread implementation is restrained by their relatively low efficiency (10-15%). The generated electrical energy produced can be used to power on-board electrical systems, traction electric motors, fuel heating, etc. Thus, electric fuel heaters have a power of up to 0.28 kW [13]. Today, several projects of TEG integration in cars are being implemented. These include the Ford Fusion 3.0-V 6, BMW X6, Chevrolet Suburban, Renault Trucks, etc. Standard-sized series of TEGs are being developed, which differ in power for different types of cars: for diesel passenger cars--200...300 W; for gasoline passenger cars--500 W; for trucks--1000 W. It is expected that the specific price of TEG will be at the level of 0.3..1.3 USD/W [14; 15; 16; 17]. The current specific cost of TEG stands at approximately EUR 8.4 per watt. The acceptable range of specific costs has been estimated to be from EUR 0.5 per watt for gasoline vehicles to EUR 3 per watt for standard diesel taxis. Some research institutions are striving to develop low-cost modules with the goal of reaching USD 1 per watt. Consequently, TEGs are not currently a financially viable option for agricultural machinery (Figure 1). The idea of injecting hot water is promising. For example, Alfa Power Systems B.V. (Bakersfield, CA, USA) has developed SwirlFlash technology. SwirlFlash is a combustion technology mainly used in gas turbines to improve fuel efficiency and reduce emissions. It involves the use of a swirl mixer combined with a flash vaporization process, where liquid fuel is mixed with superheated steam before being injected into the combustor. This process improves fuel atomization and mixing, resulting in more efficient combustion with lower levels of nitrogen oxides (NOx) and other pollutants. SwirlFlash technology is particularly beneficial in applications where fuel flexibility and low emissions are critical,such as in engines. The improved mixing and vaporization provide a more complete burn, resulting in achieving higher thermal efficiency and lower environmental impact compared to conventional combustion methods. Its principle is simple and effective.