Category Archives: Particle Image Velocimetry (PIV)

Study on Integrated Heating Technique of the Solar Pond

Jinlong Cao

Ke Yuan New Energy Tech. Development Co. Ltd.

No.177 Wo long dong jie, Wei Fang city, Shan dong province, 261061 P. R.CHINA

jlc@public. wfptt. sd. cn

The Chinese initial example of integrated heating system of the solar pond functions on the bank of Lai zhou Bay of Wei fang city, Shandong province. Adopting the heat of sea-water solar pond, shallow-styled solar pond and conservatory-modeled solar pond to initiate the technique, the system realizes the over-wintering of the cultured in the sea-water of warm water kind successfully. The way of heating in the course of nursing young aquatic products originates a new technique of the protection-styled aquaculture of solar energy. The essay introduces the technical parameters and phase achievements of the system operation, analyzes the prospect of application and dissemination, expounds the scientificalness and reasonability of the task and raises the shortcomings.

0. Introduction

Transforming the passive fishery into the active fishery is a prominent symbol of the research and development of the modern sea fishery project. It is beneficial to develop the increasing aquaculture energetically. The project exerts extensive and comprehensive intervention towards the biological process and various forms of the perching organisms in the sea and chooses the cultivation objects of high economic value in the use of modern technology: 1) Increase aquatic objects and release them to the sea. Make full use of the resource of natural baits in the sea to develop pasture-styled aquaculture. 2) Implement the industrialized development project of aquaculture along the coast of the sea.

Then, a big difficult problem aquaculture industry faces is how to solve the problem of over-wintering of the parent and young aquatic products in the seawater of warm water kind. Heating working water body by regular energy has many shortcomings, such as enormous investment, high energy-consuming, environmental pollution, high over-wintering cost and low investment repayment, so it doesn’t apply to the Chinese conditions and is unadoptable.

Taking all the situations into account, we put forward the plan of the integrated heating project of the solar pond, which studies and develops the integrated technology of unpolluted energy, solves the problem of the over-wintering of the cultivation objects in the sea water of warm water kind in the southern area of China and studies and develops the new technical supporting system to build “on-the-sea China”.


1. The overall technical scheme

1.1 Implementation picture of the integrated heating project of the solar pond.

1.2 Block diagram of the integrated heating project of the solar pond.

1.3 The brainstorm technical project of the integrated heating project of the solar pond.

Fig.1 Implementation picture. integrated heating project of the solar pond.


Mathematical formulation

The fluid flow and heat transfer in the cavity is assumed to be governed by the Navier-Stokes equations together with the energy equation with the following restrictions: steady state, laminar flow, Newtonian fluid behaviour, negligible viscous dissipation and without radiation effects. Effect of variable physical properties with temperature has been considered. The corresponding differential equations in cartesian coordinates and three dimensions can be represented by the following tensor notation:

д(рТ) д(рТ) _ к d2T

dt + U’ dxj cp dx2

The air layer is bounded by two sides at constant temperature and the remaining sides are assumed to be adiabatic. Thus the air layer is subjected to Dirichlet boundary condition on top and bottom surfaces, both being at a fixed hot and cold Tc temperatures respectively. The remaining faces are subjected to Neumann boundary condition.

A non-dimensionalization of the governing equations and the boundary conditions shows that Nusselt number depends on the Rayleigh number, the aspect ratio in both planes, Prandtl number and the inclination. Thus:

= /( )

where the Rayleigh number is defined as Ra=gf3(Th — Tc)b3/v2 and is evaluated at the mean temperature.

Basic diagram of the hybrid solar system

The dimensions of the lair equipped with the hybrid solar system are: L=50m (length), l=10m (width), h=3m (height), V=1500m3 (see Figure 2). The front of the lair has the area A’=L*h=150m2 and is oriented towards South. The Trombe wall with an area of 100m2 divided into nine equal sectors of 12m2 each is on the South front. On the same front there are eight sections of Trombe walls each with a side of 0.3m, which have the role of ventilation shafts. On the sloping roof eight solar collectors (with the role of daily heating) are installed, each with a collecting area of 4m2.

On the ground, sided to the building, five hot water storage tanks and five solar stills are installed. The PV system is installed close to the solar thermal collectors on the roof.

1. solar air collectors, 2. Trombe wall, 3. storage tank, 4. solar water collectors, 5. sloping
roof, 6. fans for cold or warm air flow direction, 7. fans for air dispersion from solar
collectors, 8. expansion bowl, 9. metal foil spool, 10. solar still, 11. collecting water trough,

12. drinking water pond

Energy supplied by the solar hybrid system

For calculating the useful energy to be supplied by the solar hybrid system, the measurements concerning the meteorological and efficiency values of the energy chain are considered:

• Average solar radiation intensity in the plane of solar air collectors is <GR>=464W/m2

• Average solar radiation intensity in the plane of Trombe wall is <G’>=312W/m2

• Number of days in a favourable (for system operation) year is Z=120days

• Average time for daily sunshine is n=8hours, that means that yearly utilization time is T=3600Z*n=3.46*106s

• Average efficiency of air solar collector taking into account the electric energy consumed by the air drive turbine is p=0.43

• Average efficiency of the Trombe wall for delayed heating is r|2=0.14

• Efficiency of the storage tank is r|3=0.50 and it is heating water by AT=15°C

• The fluorescent lamps are working 4 hours per day

• The PV modules will supply for illumination the specific power of 1.6 W/m2

• The used energy to be supplied by the hybrid solar system is Qi, u=6075 kWh/year (air solar collectors)

• Q2,u=4198kWh/year (Trombe wall)

• Q3,u=86kWh/year (water storage tank)

• Q4,u=52.7kWh/year (solar still)

• Q5,u=1168 kWh/year (PV panels)

The total useful energy is Qt, u=11579.7kWh/year.