**1. Introduction**

Solar radiation and environmental temperature measuring represent a complicated problem, as it includes unpredictable weather conditions for designing the solar system heating, which involves solar system components' dimensions exact defining. There are three categories considered upon solar heating systems designing. The first category belongs to the system, in which the collector's working temperature is known or it might be assessed, for which radiation critical levels can be revealed.

The second category is based on the big amount of detailed simulations and presents the F-diagram method.

The third category includes the short circuit simulation, in which the modeling is fulfilled by means of meteorological data for representative days and it is called the sol cost method [1].

In this experiment [2], eight typical Taiwanese solar water heaters, which were connected in series, were considered. The degree of temperature stratification and consumption of thermosyphon in a horizontal tank is estimated. The system was tested without load, with interruptions and constant load conditions. The results showed that stratification of the state was observed in tanks under load.

The researchers compared the gap filler in the results on the scale of complexity in the simulation program from the programs F-diagrams [3].

In the study [4], referring to the method of F-diagrams calculated coefficient of thermal characteristics of the solar collector.

Usage of F-diagram method for active premises heating systems applying the working liquid is the thermal research basis [1]. Applying this method thereof we can assess the fraction of total heating load, which can be provided by the solar energy system. In the method the primary project variable is a collector's square, and the secondary variables are accumulator capacity, collector type, dimensions of heat exchanger load and collector and liquid flow speed. F-diagrams have been developed for three system standard configurations: liquid and air, used for premises heating (and hot water) and systems for only hot water [1]. In this study [5], solar systems are analyzed using the F-chart method in order to satisfy the hot water needs of hotels. The annual fraction and heat loads for different solar collector's area and number of people is estimated. Flat plates and vacuum tube collectors are compared and analyzed.

Kalogirou used for protection from freezing water ethylene glycol, necessary for solar heating system operation [6].

removed from a collector, and instead of it there incomes cold water from the water pipeline with a valve for cold water (8) and from the syphon of а dosimeter tank (7) there takes place constant thermosyphon circulation by means of circulation tube (10). Further the liquid enters a thermal pump (11), which consists of a condenser evaporator (12) with temperature t2, with a heat exchanger in the form of a spiral, absorbing the heat carrier heat, lowers its temperature down the atmospheric temperature (Q2) using the speed control valve (14), thereby serving to the heat additional absorption from the atmospheric air. The scheme also shows the solar irradiation, reflected from semi translucent cover (Q0) and an absorbing panel surface (Q1). In the thermal pump there is fulfilled a heat exchanger energy transfer, at respectively low temperature, to a condenser heat exchanger's heat carrier (15) in the form of a spiral with higher temperature t2, which increases the square, as well, a heat exchanger intensity. To execute the cycle thereof we use a compressor (13) with temperature t3, with an electric drive (17). Hereafter, by means of a condenser heat exchanger (15) with temperature t4, the heat from a thermal pump (Q5) is transferred to a heat exchanger's accumulator tank Q6 with temperature t6of the heating system (18). As the installation has two circuits, it is provided with automatic circulation pumps (19, 20) for liquid circulation between the solar collector and evaporator, condenser and accumulator tank. The water temperatures brought to the demanded technological level and supplied to a consumer for water

*F-diagram Research Method for Double Circuit Solar System with Thermosyphon Circulation*

*DOI: http://dx.doi.org/10.5772/intechopen.88045*

*Principal diagram of double circuit solar installation with thermosyphon circulation.*

**Figure 2** demonstrates the model of the flat solar collector. The main point and novelty is in the fact that in distinction from the known designing principle, the collector contains a translucent glazing unit (2) with double glass and reduced pressure, as well as a parametric frame (1). A wooden frame's bottom (7) has been made of plywood with 8 mm thickness and stuck a heat sealing film (5) with foil. In the gap between a glazing unit and frame's bottom there has been laid a flexible 4ϕ16 mm thin walled stainless corrugated pipe in the coil form. Pipe edges are

**Figure 3** shows a flat solar collector's mockup. The solar collector is the main heat generating unit of the solar installation. To reach a preset aim we have developed a principally new flat solar collector, based on which there will be constructed various types solar installations, used for water heating and buildings and premises

attached to the inlet and outlet protruding tubes (6) (**Table 1**).

provision and heating.

**Figure 1.**

heating.

**53**

In order to assess the solar energy potential, falling onto the territory in any region, it is necessary to have data on the solar energy potential. Based on actual observations and theoretical computations generalization we can obtain the following data: annual and latitudinal movement of potential monthly and annual sums of direct solar radiation, falling onto the perpendicular surface under the clear sky conditions; the data on sun shine duration; sunshine daily move; radiation for the annual typical days; maps of distributing the average monthly radiation amounts for June and December on Kazakhstan territory [7].

In the article herein, using the F-diagram method, the authors have designed the solar heating system and definition of total thermal load fraction (load on household water and heating), which will be supplied with solar energy with a view to the family, consisting of six people in Almaty city. The research includes the influence of the collector's different squares and storage capacity per the collector square meter and collector tilter the load share, maintained by the solar energy. As well, there will be studied an annual behavior of solar load share and monthly load change within a year.

### **2. System description**

System's standard configuration, used in the given work frame, to which the F-diagram method will be applied, has been shown on the **Figure 1**. The system herein makes use of the liquids (commonly, water or antifreeze solution) as a heat carrier and water as a storage medium [5]. Flat solar collectors with thermosyphon circulation are used for transforming the falling solar radiation into the thermal heat. The energy thereof is accumulated in the form of notable heat in the tank for the liquid storage and used, when the need arises, to provide premises and water heating.

Proposed system operation is executed as follows (**Figure 1**). The solar energy E with temperature t0 is absorbed by solar collector (1) with temperature t1, heating the flow, the solar energy moves through a translucent insulating glazing unit (2). The heat, received from the solar stream, heats the liquid in coils (3), which is

*F-diagram Research Method for Double Circuit Solar System with Thermosyphon Circulation DOI: http://dx.doi.org/10.5772/intechopen.88045*

#### **Figure 1.** *Principal diagram of double circuit solar installation with thermosyphon circulation.*

removed from a collector, and instead of it there incomes cold water from the water pipeline with a valve for cold water (8) and from the syphon of а dosimeter tank (7) there takes place constant thermosyphon circulation by means of circulation tube (10). Further the liquid enters a thermal pump (11), which consists of a condenser evaporator (12) with temperature t2, with a heat exchanger in the form of a spiral, absorbing the heat carrier heat, lowers its temperature down the atmospheric temperature (Q2) using the speed control valve (14), thereby serving to the heat additional absorption from the atmospheric air. The scheme also shows the solar irradiation, reflected from semi translucent cover (Q0) and an absorbing panel surface (Q1). In the thermal pump there is fulfilled a heat exchanger energy transfer, at respectively low temperature, to a condenser heat exchanger's heat carrier (15) in the form of a spiral with higher temperature t2, which increases the square, as well, a heat exchanger intensity. To execute the cycle thereof we use a compressor (13) with temperature t3, with an electric drive (17). Hereafter, by means of a condenser heat exchanger (15) with temperature t4, the heat from a thermal pump (Q5) is transferred to a heat exchanger's accumulator tank Q6 with temperature t6of the heating system (18). As the installation has two circuits, it is provided with automatic circulation pumps (19, 20) for liquid circulation between the solar collector and evaporator, condenser and accumulator tank. The water temperatures brought to the demanded technological level and supplied to a consumer for water provision and heating.

**Figure 2** demonstrates the model of the flat solar collector. The main point and novelty is in the fact that in distinction from the known designing principle, the collector contains a translucent glazing unit (2) with double glass and reduced pressure, as well as a parametric frame (1). A wooden frame's bottom (7) has been made of plywood with 8 mm thickness and stuck a heat sealing film (5) with foil. In the gap between a glazing unit and frame's bottom there has been laid a flexible 4ϕ16 mm thin walled stainless corrugated pipe in the coil form. Pipe edges are attached to the inlet and outlet protruding tubes (6) (**Table 1**).

**Figure 3** shows a flat solar collector's mockup. The solar collector is the main heat generating unit of the solar installation. To reach a preset aim we have developed a principally new flat solar collector, based on which there will be constructed various types solar installations, used for water heating and buildings and premises heating.

consumption of thermosyphon in a horizontal tank is estimated. The system was tested without load, with interruptions and constant load conditions. The results

The researchers compared the gap filler in the results on the scale of complexity

In the study [4], referring to the method of F-diagrams calculated coefficient of

Kalogirou used for protection from freezing water ethylene glycol, necessary for

In the article herein, using the F-diagram method, the authors have designed the solar heating system and definition of total thermal load fraction (load on household water and heating), which will be supplied with solar energy with a view to the family, consisting of six people in Almaty city. The research includes the influence of the collector's different squares and storage capacity per the collector square meter and collector tilter the load share, maintained by the solar energy. As well, there will be studied an annual behavior of solar load share and monthly load

System's standard configuration, used in the given work frame, to which the F-diagram method will be applied, has been shown on the **Figure 1**. The system herein makes use of the liquids (commonly, water or antifreeze solution) as a heat carrier and water as a storage medium [5]. Flat solar collectors with thermosyphon circulation are used for transforming the falling solar radiation into the thermal heat. The energy thereof is accumulated in the form of notable heat in the tank for the liquid storage and used, when the need arises, to provide premises and water

Proposed system operation is executed as follows (**Figure 1**). The solar energy E with temperature t0 is absorbed by solar collector (1) with temperature t1, heating the flow, the solar energy moves through a translucent insulating glazing unit (2). The heat, received from the solar stream, heats the liquid in coils (3), which is

In order to assess the solar energy potential, falling onto the territory in any region, it is necessary to have data on the solar energy potential. Based on actual observations and theoretical computations generalization we can obtain the following data: annual and latitudinal movement of potential monthly and annual sums of direct solar radiation, falling onto the perpendicular surface under the clear sky conditions; the data on sun shine duration; sunshine daily move; radiation for the annual typical days; maps of distributing the average monthly radiation amounts

Usage of F-diagram method for active premises heating systems applying the working liquid is the thermal research basis [1]. Applying this method thereof we can assess the fraction of total heating load, which can be provided by the solar energy system. In the method the primary project variable is a collector's square, and the secondary variables are accumulator capacity, collector type, dimensions of heat exchanger load and collector and liquid flow speed. F-diagrams have been developed for three system standard configurations: liquid and air, used for premises heating (and hot water) and systems for only hot water [1]. In this study [5], solar systems are analyzed using the F-chart method in order to satisfy the hot water needs of hotels. The annual fraction and heat loads for different solar collector's area and number of people is estimated. Flat plates and vacuum tube collectors are

showed that stratification of the state was observed in tanks under load.

in the simulation program from the programs F-diagrams [3].

thermal characteristics of the solar collector.

*Thermodynamics and Energy Engineering*

compared and analyzed.

change within a year.

heating.

**52**

**2. System description**

solar heating system operation [6].

for June and December on Kazakhstan territory [7].

#### **Figure 2.** *Flat solar collector.*


#### **Table 1.**

*Technical specifications of flat solar collector.*

**Table 2** represents the ranges of the basic project variables, used upon developing the correlations for liquid solar system heating [1].

mode of thermosyphon circulation double circuit solar collector. Proceeding from the analysis results we have managed to optimize individual structural elements, as well to prognoses the thermal regime and alternative solutions selection for design-

Solar heat supply system's energy balance for the month period can be presented

where *Q* is the solar installation monthly heat production, *Q <sup>h</sup>:ws* is the hot water supply monthly load, Е is the energy total amount, obtained within a month, and

*Q* ¼ *Q <sup>h</sup>:ws* þ *E* ¼ Δ*U* (1)

\*K

ing the flat solar collectors and their operation regime selection [9].

*Construction parameters ranges used upon developing F-charts for liquid systems [5].*

**Parameter Range** ð Þ *τα <sup>n</sup>* 0.6–0.9

*F-diagram Research Method for Double Circuit Solar System with Thermosyphon Circulation*

*DOI: http://dx.doi.org/10.5772/intechopen.88045*

RAC 5-120 m<sup>2</sup> UL 2.1–8.3 W/m<sup>2</sup>

*β*ð Þ collector slop 30–90° (UA)h 83–667 W/K

ΔU is the energy amount change in the accumulating unit.

**3. F-chart method**

as [1]:

**55**

F/

**Figure 3.**

*Mockup of flat solar collector.*

**Table 2.**

The authors have elaborated a new computation methodology and selection of thermosyphon solar collector's geometrical parameters. As well, there has been shown the dependence of the tube's cross section on the flow time for different pressure values. Along with the syphon head increase there the liquid flow time grows as well. It is explained with the fact that the syphon hydraulic resistance increases along with pressure increase, which brings to the liquid speed reducing. For the first time there has been formulated the dependence, defining the fluid discharge time according to the solar collector's geometrical parameters. The methodology, having been elaborated, has allowed stating that the local hydraulic resistance and friction play a sufficient role in a heat carrier's expenditures [8]. Also we have considered the mathematical model of separate constructions and operation

*F-diagram Research Method for Double Circuit Solar System with Thermosyphon Circulation DOI: http://dx.doi.org/10.5772/intechopen.88045*

**Figure 3.** *Mockup of flat solar collector.*


**Table 2.**

**Table 2** represents the ranges of the basic project variables, used upon develop-

Insulation Foam plex (foam polyurethane)

Collector tilt 45° Absorber's heat transmission capacity 401 W/(m K) Insulation heat transmission capacity 0.04 W/(m K) Transmission-absorption factor 0.855 Sun visual temperature 4350 K Atmospheric temperature 303 K Radiation intensity 1000 W/m2

**Parameters Value** Absorbing plate material Copper Absorbing plate dimensions 2 m 1 m Plate thickness 0.4 mm Glazing material Hardened glass Glazing dimensions 2 m 1 m Glazing thickness 4 mm

The authors have elaborated a new computation methodology and selection of thermosyphon solar collector's geometrical parameters. As well, there has been shown the dependence of the tube's cross section on the flow time for different pressure values. Along with the syphon head increase there the liquid flow time grows as well. It is explained with the fact that the syphon hydraulic resistance increases along with pressure increase, which brings to the liquid speed reducing. For the first time there has been formulated the dependence, defining the fluid discharge time according to the solar collector's geometrical parameters. The methodology, having been elaborated, has allowed stating that the local hydraulic resistance and friction play a sufficient role in a heat carrier's expenditures [8]. Also we have considered the mathematical model of separate constructions and operation

ing the correlations for liquid solar system heating [1].

*Technical specifications of flat solar collector.*

*Thermodynamics and Energy Engineering*

**Figure 2.** *Flat solar collector.*

**Table 1.**

**54**

*Construction parameters ranges used upon developing F-charts for liquid systems [5].*

mode of thermosyphon circulation double circuit solar collector. Proceeding from the analysis results we have managed to optimize individual structural elements, as well to prognoses the thermal regime and alternative solutions selection for designing the flat solar collectors and their operation regime selection [9].
