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Pulsating heat pipes (PHP) are high efficient heat transfer devices and one of the novel types of heat pipes. Applying of such heat pipes as main heat transfer elements of recuperative heat exchangers, which are widely used in power engineering, energy saving, chemical and food industry, is one of perspective ways. Heat transfer characteristics of such apparatus depend on many factors. Flow rate of heat carriers can be named as one of the most important among them. That’s why investigation of its influence on characteristics of these heat exchangers is necessary. Providing of such investigation not only on whole heat exchanger, but also on its main elements, i.e. PHP, is expedient for better understanding of these influences. And studying on single loop PHP allow to eliminate effect of other turns. Results of experimental investigation of cooling medium influence on heat transfer characteristics of copper single loop PHP with water as heat carrier and filling ratio of 45 % are presented in this work. Inner diameter of PHP was 3,1 mm, overall length – 212 mm, length of heating zone – 70 mm, length of condensation zone – 142 mm. PHP was investigated in vertical bottom heating position in the range of input heat power 10-140 W. Flow rate of cooling water was 2,9-7 g/s and its temperature 10-15°C. As a result of provided investigation it was found out that temperature difference and thermal resistance of PHP is 20-22 % lower and transferred heat power 35 % higher at flow rate of 2,9 g/s than these ones at the higher values of flow rate. Flow rate changing in the range 4,5-7 g/s has no significant influence on temperature difference and thermal resistance of PHP. Based on this, decreasing of cold heat carrier flow rate can be recommended for increasing of heat transfer coefficient in heat exchangers based on PHP. [ABSTRACT FROM AUTHOR]

An article is devoted to the study of maltodextrin as an object of spray drying in the system "dropvapor medium" at an experimental apparatus for drying single droplets in a flow of heat transfer agent. Liquid maltodextrin concentrate containing 78-83% dry matter is characterized by a high-viscosity consistency, which causes complications in many technological processes. Obtaining it in the dry powder form by spraying will improve its conditions of use and expand its application. The presence of sugary substances, which are present in mildly acidic solutions, сontributes to the manifestation of properties typical for amorphous substances and polymeric materials. This is the reason why maltodextrin belongs to the category of thermoplastic materials which are ones of the most difficult spray drying objects. The drying ability of the maltodextrin coloid system as well as the adhesion of the dried particles in the spray dryer chamber are inherent in its physicochemical characteristics and rheological properties. It is they that determine the kinetics of drying droplets of the solutions, morphology and strength of the dried particles under the influence of different temperature parameters. Studies of drying droplets of maltodextrin solutions having a mass fraction of reducing sugars of 38-42% were carried out at concentrations of 40%, 45%, 50%, 55% and 60% of dry matter and heat transfer agent temperatures of 140°C, 160°C, 180°C and 200°C. It has been determined that when the solutions are ≥ 50% dry matter and the heat transfer agent temperatures rises to 200°C, an instant increase in the concentration and pressure gradients on the surface of the dense impermeable shell of the hanging drop occurs which is typical for coloid systems. These facts are evidenced by the photographic materials of various changes in the shape, size and structure of droplets in the stages of boiling and drying. Moreover, a sharp increase in diffusion resistance to moisture transfer results in the retention of residual moisture inside the droplet. This fact is confirmed by boiling of water vapor in the form of bubbles which emerged from the holes of the drops during their probing in the flow of heat transfer agent. It was recorded when studying the physical state of dried droplets (particles) of the solutions (≥50%). A higher capacity to dry to a dry state, which was determined from the kinetic dependences of the relative duration of droplets dehydration to the critical point 3, was found for solutions with a concentration of <50% at heat transfer agent temperature of 180-190oС. However, the dried droplets of any of investigated maltodextrin solutions in the flow of heat transfer agent were in a viscous-plastic state and revealed adhesion. An analysis of the physical state of dried drops of maltodextrin in the flow of the heat transfer agent and beyond its boundaries allowed to establish that only after cooling did the particles become solid without adhesion properties (20°С). [ABSTRACT FROM AUTHOR]

Ukraine has a high level of industry, agriculture and consumption. As a result of underutilization of recovered materials and their products into the environment returns significant amount of waste that contaminate soil, water, air. Dumps occupy large areas, long ground beneath them put out of production, they pollute the environment. The main causes of waste, lack of effective processes and capacities of processing residues, spatial and chronological dissociation processes of waste and their use, lack of sufficient market. Of all the organic waste in Ukraine is one of the main places belong chicken droppings. Fresh droppings quickly oxidizes the soil, humus and inhibits microorganisms, disrupting its natural ecosystem biological community. With some preparation and processing of chicken manure is a high quality fertilizer that contains chemical elements (N, P, K), macro- and micronutrients, humic acid and other components that are essential for growth and fertility of different plants. For decontamination litter widely used thermal drying at t = 600 – 800 °C. This product is well kept dry, easily transported, but using traditional drying facilities for its handling used large amount of heat. Today continually created and offered new modern technologies for processing chicken manure. At the Institute of Engineering Thermophysics NAS of Ukraine many years conducted investigations on the creation of modern technologies and equipment for processing organic waste. Analysis of the traditional intensification methods and processes of heat and mass transfer during drying of materials was presented in the paper. The author has proved the promising nature of the method of the combined processes of drying and dispersion using a mechanical rotor to intensify the process of drying of high–moisture thermolabile materials. [ABSTRACT FROM AUTHOR]

The results of experimental researches of the heat exchange process in the device with a rotary screw thermosyphon are presented. The works of rotary heat exchangers for heat treatment of raw materials, heat exchangers with rotating heat pipes are considered. Deficiencies of the equipment are defined. It is proposed to use devices based on rotary thermosyphons for heat treatment of food liquids. From the point of view of reliability these devices are more effective as are independent designs. The surface of the rotating thermosiphon allows to realize local energy influence directly on a boundary thermal layer in a product. It is shown that it is expedient to conduct a study of heat transfer processes in such devices. Experimental stands and research methods have been developed. An experimental setup for modeling the movement of condensate inside the condenser of a screw rotary thermosyphon has been developed. An experimental setup has been developed to study the heat transfer process in the "thermosiphon-product" system. The modeling of the internal and external heat transfer problem for the screw rotary thermosyphon is carried out. The external problem takes into account the hydrodynamics and heat and mass transfer during the flow of the thermosyphon condenser product, the internal problem - the hydrodynamics of condensate movement inside the condenser. The use of a screw capacitor gives a number of advantages - simultaneous mixing, heating, transportation of the product. Also, unlike a branched capacitor, in the screw there is no locking of the condensate under the action of centrifugal force. Studies on the modeling of hydrodynamics have shown that for the screw thermosyphon return of condensate to the evaporator, the internal heat exchange will be most effective at angles of inclination of the condenser 37... 45 deg. It was found that the angle of the rotary thermosyphon affects the heating dynamics of the product. The greater the angle of inclination, the faster the product heats up. This is due to the effective return of condensate and reduction of thermal resistance. The results will be used to develop methods for calculating devices based on rotary thermosyphons. [ABSTRACT FROM AUTHOR]

In current paper technological problems of the food technologies perspective direction - cubic form dumplings production are discussed. Designs of traditional devices and production lines for making dumplings are analyzed. The proposed hypothesis is that the energy consumption in dumplings production can be reduced by using of formed and frozen forcemeat in the aggregate. The design and principle of operation of the developed robotic complex for the production of 22x22x22 mm dumplings are given. The stages of the thermomechanical cycle of forming and heat treatment of workpieces and quality control of finished products are analyzed. The modular-process scheme of the developed complex is presented. The complexes of parameters that characterize key operations at dumplings production are defined. The ranges of temperature and time parameters changes are given, the tasks for control systems are substantiated. Static balance energy models are determined. The parametric and thermophysical models of thermomechanical processes in the apparatus are considered. The task is formulated and analytical modeling of the thermal state of the main elements is carried out: forcemeat, dough, grabs and the environment. The single-valuedness conditions and boundary conditions are given. The model of thermal resistances for the stages of switched on and off heat elements is obtained by the methods of electrothermal analogy. The method for solving a nonstationary heat transfer problem involving similarity numbers is proposed. The results of experimental modeling of cooling and freezing kinetics of forcemeat in the dough are presented. The level of cryoscopic temperatures for forcemeat and dough was determined. The thermograms of the heater heating in the forcemeat blank in the dough are analyzed. [ABSTRACT FROM AUTHOR]

The article examines the use of heat of infrared radiation, which is one of the effective ways to intensify the heat treatment of sausage loaves and can significantly reduce the duration of its processing and improve the quality of finished products. On the basis of the modern approach the solved problem is connected with thermal treatment which consists in research of those ways and the modes providing necessary inactivation of microflora, the maximum preservation of nutritional value of a product. Based on certain prerequisites, a mathematical model of joint heat and mass transfer and heat treatment of cylindrical sausage loaves in a frying unit with infrared (IR) heating is considered. The following methods and regimes have been studied, which would ensure, together with the necessary inactivation of harmful microflora, the maximum preservation of the nutritional value of the product. A set of parameters that have a direct impact on the course of the thermal action on sausage loaves has been studied. The attenuation of the radiant flux entering the product, which is described by the parabolic law, is taken into account. Implemented effective ways to intensify the heat treatment of sausage loaves using energy and improve the quality of finished products based on a mathematical model of the thermal electromagnetic field of the IR range. The problem of joint heat and mass transfer during infrared heating of a cylindrical sausage loaf is set and analytically solved. The obtained results will allow to calculate the fields of temperature and moisture content, the average values of the corresponding transfer potentials, heating temperature, heat consumption in the heat exchange process, as well as to obtain formulas convenient for engineering calculations. The proposed analytical constructions make it possible to determine the time required for the product to reach a certain temperature and moisture content, providing weight loss during drying in the range of 0.5-1.8 % with a duration of the process from 3 to 30 minutes. [ABSTRACT FROM AUTHOR]

Due to the scarcity and high cost of products from valuable species of fish, there is a need to produce their analogues, which in terms of nutritional value and taste would not be inferior to natural products. One of the methods for producing analogue of black caviar consists in the monodisperse crushing of a jet of solution prepared on the basis of the protein of chicken eggs with natural fish additives and black food coloring. Drops of the solution are sent to the granulation column, where they are heated to the temperature of the beginning of thermal coagulation of its protein component. The creation of isothermal conditions in the granulation column and the reduction of heat losses from its surface in order to increase the energy efficiency of the production are important problems encountered in the production of granulated products using this technology. To solve these problems, the temperature regime of the granulation column in the production of imitated monogranular food products has been studied using a numerical simulation method. By numerical solution of the system of equations of hydrodynamics and heat transfer for the flow of the forming liquid, the velocity and temperature distributions in the granulation column are obtained. The distance that a particle must pass in the granulation column to complete its gelling process has been found. The effect of thermal insulation of a column on heat loss from its surface is shown. [ABSTRACT FROM AUTHOR]