Category Integrated Greenhouse Systems for Mild Climates

Mean daily temperature

Fig. A.5 Means of daily global radiation for Agadir (Morocco), Gafsa (Tunisia) and Almeria (Spain)

Annex B

Calculation of fuel consumption in Sect. 12.2.

1. Almeria, Spain (36°50’N).

tid = 16°C, tst = 2°C, u = 7 W/(m2 K), Ac/Ag = 1.33, see 12.5. Mean night temperature (°C)

tmmin according to Miiller (1996)

A tmaxd—tmind (Miller 1996)

£/n/(24-dj) Table12.3 (Hallaire 1950),

dj = mean daylight hours = /(latitude, month) according to Allen et al. (1998).

Fuel consumption tid = 16°C.

Qmonth (kWh/m2 month) = accor...

Based on the experience with the simple solar water desalination systems a closed – system greenhouse with integrated solar water desalination was developed and evaluated first in a small greenhouse (Strauch 1985a, b), and then in a pilot plant designed in Germany, and erected and evaluated at the University of Adana, Turkey (Baytorun et al. 1989; Meyer et al. 1989). The greenhouse was designed to fulfil the following demands:

• Plant production in arid regions in a controlled environment with protection from wind, dust and low air humidity.

• Inside air temperatures which do not exceed suitable conditions for plants, even at high outside radiation and temperature.

• Reduction of water use by decreasing transpiration rate, and reduction of humidity losses through air exchange by making...

Salt water is heated up by solar energy in a basin or at an wetted absorber surface; the water evaporates and condensates on a transparent colder material that should be opaque to long-wave radiation (Figs. 15.1-15.4). The condensate runs down on the sloped surface into a gutter. The aim is to use as much solar energy as possible, and to design a simple and cost-effective construction with low maintenance and running costs. Only commercially available construction components, if possible greenhouse components, should be used for the design. A completely sealed system and good insulation to the soil are prerequisites for high efficiency. Losses are due

C. von Zabeltitz, Integrated Greenhouse Systems for Mild Climates,

DOI 10...

The availability of sufficient irrigation water is a big problem in many arid and remote areas. The irrigation water for crop production in greenhouses will be provided by seawater desalination plants in some countries, which use oil for the necessary desalination energy. In Kuwait, for example, trucks transport irrigation water from sea water desalination plants to the greenhouse holdings. The water from desalination plants is relatively expensive, and is used mainly for human consumers.

Brackish or salty water is available in many arid regions. If greenhouse systems for reduced irrigation water requirement (closed-system greenhouses) and cost – effective solar water desalination systems can be developed, vegetable production can be extended to those arid regions.

A closed-system greenhou...

Different types of storage basins can be built, if enough space is available near the greenhouse:

• Simple basins, dug in the soil, if the soil at the bottom of the basin is sufficiently watertight.

Table 14.2: Calculation of the storage volume for the collection of precipitation in Antalya (Turkey). Precipitation Pre (Muller 1996); STPm with (14.5) and EVpond = 0; ET0 from Fig. 13.1. CWRm=1.04 x ET0 x dm (see Example 1)

STPy = Epos STPm = 608.2 l/(m2 year)

Defy = Eneg STPm = 1,651.4 l/(m2 year)

STPy > CVmmax:

Case 2(a): Storage volume VST = STPy = 608 l/m2

The storage is empty from July until October. The crop water requirement can be covered for 8 months from November to June by rainwater with a storage volume of 0.61 m3/m2 greenhouse area.

Table 14.1: Calculation of the storage volume for collecting rainwater for irrigation in Bangalore (India). Precipitation Pre (Muller 1996); Monthly storable precipita­tion STPm with (14.5) and EVpond = 0; ET0 see Fig. 13.1;

CWRm = ET0 X kc(1 + h) x AqMg X dm

For tomato, mean kC = 1.1; (1 + (;) = 1.05; ACr/AG = 0.9

kc(1 + (i) x Acr/AG = 1.04;

CWRm = 1.04 x ET0 x dm From Table 14.1 can be seen:

STPy = Epos STPm = 164.9 l/m2 year Defy = Eneg STPm = 371.2 l/m2 year

The following points have to be considered for the design of the storage basin:

• The area of greenhouses and the vacant area available for a storage basin.

• The distribution of precipitation and the amount of rainfall.

• The crop water requirement.

• Whether the storage basin is only to be used for storing rainwater or for mixing rain and salty water.

Normally, daily frequencies of precipitation should be taken into consideration for the calculation of the storage volume. Those values are unknown in most cases. Therefore, monthly precipitation can be used to estimate the storage volume in a first approximation.

The monthly collected amount of precipitation is.

CVm = Pre x fC (l/m2month), (14.4)

where

Pre (l/m2month) = mean monthly precipitation fC = 0...