Heating installation of sewage water with solar captor.

Pop, Petru ; Veres, Mircea ; Iancu, Carmen 等

1. INTODUCTION

The installations of sewage water heating with boilers mounted in parallel have used in apartments, buildings and houses. The boilers have mounted so in primary thermal circuit, which circulated through boiler serpentine pipes and each on consumption water circuit (Ungur et al, 2008).

The circulation of primary agent by inner boiler serpentine's pipes has done by gravitation due to thermal pressure or with pumps. At circulation by gravitation, the boilers have mounted at predicted height, which at pumps this condition it's not necessary. The cold water has taken through a pipe and received heat from primary thermal agent by exchange surface of serpentine. The warm water of consumption, heated at 60-65[degrees]C is served out at tap by a connection pipe. In our case, the heat flow has got by a solar captor and transmitted at water storage in boiler, which is working in storage-recuperate state (Chardonnet, 1973; Maghiar, 1995).

The heating installation of domestic water with thermal solar captor and storage-recuperate boiler is simple and easy to build up, great efficiency and large perspective for future.

2. THEORETICAL ASPECTS

In hydraulic circuit by thermal pressure is getting in recuperate-storage boiler, which is standard. The normal capacities of boilers are of 5, 10, 30, 50 and 100 l. The required volume for a boiler is getting by the relation (Ungur et al, 2008):

V = [Q.sub.a max]/c x [rho]([[theta].sub.c] - [[theta].sub.a]) (1)

Where: V-is necessary volume [[m.sup.3]];

[Q.sub.a max]-total maxim quantity of transmitted heat by primary thermal agent of storage water in boiler on a consumption time [J] or [kcal];

c--specific heat of warm water for consumption [J/kg x K] or [kcal/kgf x [degrees]C];

[rho]--density of warm water for consumption [kg/[m.sup.3]] or [daN/[m.sup.3]];

[[theta].sub.a]--temperature of cold water for consumption [[degrees]C];

[[theta].sub.c]--temperature of warm water for consumption [[degrees]C].

If it has taken the temperature of cold water of [[theta].sub.a] = 10[degrees]C and temperature of warm water for consumption of [[theta].sub.c] = 35-55[degrees]C, for calculus of parameters-([rho]) and (c) has taken medium warm water for consumption:

[[theta].sub.m] = [[theta].sub.a] + [[theta].sub.c]/2 = 10 + 55/2 = 32.5[degrees]C

The determination of [Q.sub.a max] transmission of storage water in boiler has calculated with relation:

[Q.sub.a max] = [Q.sub.s] - [Q.sub.c] (2)

Where: [Q.sub.s]-is heat loss of primary thermal agent (warm water by thermal captor) the water from inner installation-[Q.sub.c] and heat flow loss of water from boiler-[Q.sub.a].

[Q.sub.s] = [Q.sub.c] + [Q.sub.a] (3)

The heat flow required for preparing of warm water is getting by relation:

[Q.sub.c] = [G.sub.0] x c([Q.sub.c] - [Q.sub.a]) (4)

Where: [G.sub.0]-is hour's flow rate of warm water [l/h].

[G.sub.0] = G x N x p/100 (5)

Where: G-is daily consumption of warm water at 55-60[degrees]C [l/day/person];

N-number of people from house;

p-variation percentage of water consumption.

For a consumption of normal water-[G.sub.0] of 10, 20, 30, 50 l/day, for a small kitchen is enough using as warm source a thermal solar captor of 1-2[m.sup.2]. For specific weight of warm water for consumption [gamma] = 1000daN/[m.sup.3], at a volume of warm water of 50 l/day, is enough a heat quantity-[Q.sub.a max] of 3000 kcal/h, which can be assured by a thermal solar captor (Ardelean, 1978; Bute, 1987; Maghiar, 1995).

[FIGURE 1 OMITTED]

The scheme of thermal plan solar captor has presented in Fig. 1, where: 1-is light ray, 2,5-glass or Plexiglas, 3-capilar pipes from copper, 4-coloidal graphite, 6-aluminium foil or plate with reflexive paint, 7-plate from expandable polystyrene.

At construction of plan thermal solar stand the phenomena applications (Fig.1) of optics: A- reflection light, B-refraction and absorption light, C-reflection and refraction light, D-total reflection, E-thermo-isolate medium.

The working principal of plan solar captor consists in used of black body effect as absorbent of thermal radiation, conjugated with glasshouse effect of vacuum effect [Maghiar, 1995]. Between glass's plates of (2)-(5) from Fig.2, has exhibited intense glasshouse phenomena.

3. HEATING INSTALLATION OF SEWAGE WATER

The heating installation of sewage water with thermal solar captor and storage-recuperate boiler, with 50 l capacity, has composed from a thermal solar captor- A, and a heat storage battery -B presented in Fig.2. The thermal solar captor-A is getting in closed water circuit-1 equipped with taps, an expansion vessel-2 and a thermal resistor-4 (coil from cupper, or thermal register with porous core).

The primary circuit of agent has assured by thermal pressure. The heat storage battery-B is a simple water boiler, divided from a wall-5 in two partitions-c of cold water, and -d of warm water, being equipped with a valve and floating-3, the warm water from partition-d being heat by thermal register-4. The open storage battery-B is located up, for primary warm water permitted to rise up by thermal pressure and specific weight decreased. It is following a cold heated water circulation in adaptable boiler-B through the pipes-6 to tap, which assured the sewage warm water [Moraru&Popescu, 1978].

The novel characteristic elements consist in:

--heat storage battery-B, which is portioned and equipped with floating;

--thermal register-RT with porous core, located in storage battery, from which relieved heat from primary thermal agent at storage-recuperate boiler.

This porous thermal register substituted spirals from copper pipes used before, assured an improvement of thermal efficiency.

The thermal register is a device that realizes the heat transfer between fluid and environment, from which exist a temperature gradient. The function of thermal register with thermal resistance into a heat installation of warm water, without phase change with closed circuit is continuing.

[FIGURE 2 OMITTED]

[FIGURE 3 OMITTED]

In Fig.3 has presented a reinforced thermal register, which has composed from the following elements: 1--is metallic pipe, 2--porous ceramics parts, 3--covers, 4--couplings.

At thermal register, the heat transfer is indirect by a change surface (the wall of thermal register goes between fluid and environment).

These registers function for normal temperatures (50-150[degrees]C), and water passing by installation with a low pressure. For realized a maxim heat transfer from environment to thermal register of steel or aluminum pipe, is necessary to grow up the transport section and hydraulic pressure, with decrease of water volume from installation [Nitu, 1982; Tomescu, 1975].

These requirements can be obtain by using of porous cores with adequate thermal conductivity and optimal specific heat, located within thermal register and get in small electro-pump of water, which assured a difference of pressure required fluid circulation through a heat installation with closed circuit [Danescu, 1980; Ungur, 2008].

For the future these installations with thermal solar captor and adaptable boiler will be used on large in heating installations of domestic water, because of them ecologic action and low cost of energy.

4. CONCLUSION

The installation presented in this paper is simple, ecological and easy to build up.

The installation can used any type of thermal solar captor, with large perspective in domestic houses and warmhouses.

The thermal solar captor is safety in working, can be assembly in any position, being ecologic.

Thermal register of heat exchanger is modern, equipped with porous core, having good thermal characteristics, and higher efficiency.

5. REFERENCES

Ardelean, I. & Folescu, G. (1978), Solar Captor, Scientifically and Encyclopaedically Editor, Bucharest

Bute, A. (1987), General Energetic and Energy Conversion, Traian Vuia Polytechnic Institute

Chardonnet, I. (1973), Sources of Energy, Sirsy Editor, Paris

Danescu, A., et al. (1980), Using of Solar Energy, Technical Editor, Bucharest

Maghiar, T. (1995), New Source of Energy, University of Oradea, Keysys Editor, Oradea

Moraru, D. & Popescu, C. (1978), Solar Generators, Scientifically and Encyclopaedically Editor, Bucharest

Nitu, V. et al. (1982), General Energetic and Energy Conversion, Didactical and Pedagogical Editor, Bucharest

Tomescu, F.M. (1975), Energy Conversion and Sources, Polytechnic Institute Bucharest

Ungur, P.; Pop, P.A.; Veres, M.; Iancu, C.; Mircea Gordan, M. & Craciun, D. (2008), Thermal Registers With Core For Heated Installations With Geothermal And Heat Water, 12th International Research/Expert Conference "Trends in the Development of Machinery and Associated Technology" TMT 2008, Istanbul, Turkey, 26-30 August, 2008.