Objective
- Cooling an office building subject to a Central European climate by
a solar-thermal absorption refrigeration plant.
- Substitution of electrical power during refrigeration operation by solar
heat in summertime operation
- Substitution of refrigeration machines containing CFC by a CFC-free system.
- Substitution of fossil-fuelled heat for heating purpose by solar heating in
wintertime operation (partially).
Operation of absorption cooling machine with solar heat for extension. Energy savings in summer season : abt. 8000 KWh/month for cooling.
The planned project involves cooling the office headquarters building of J. Wolfferts GmbH in Hansestrasse (51149 Koeln-Porz) in the summertime. The building is located at a latitude of fifty degrees north.
During the course of an initial calculation, a figure of 562 W/m2 insolation was determined for July 1 at 4 pm summertime. The maximum cooling load situation of the building was determined with a computer program for July 1, 4 pm, cloudless sky. This indicates that conditions of maximum cooling load simultaneously involve the most intensive insolation. 26 deg. C was permitted as the maximum room temperature. This results in a thermal load of 81 kW to be dissipated in the entire building.
Two absorption-type fluid heat-exchanger coolers each with a heat-exchanger capacity of 46 kW have been selected in order to achieve an adequate heat-exchanger capacity. Their expellers require a heat output of 125 kW in total. A collector surface area of 206 m2 was computed in order to cover this output. Extremely well-insulated vacuum collectors with extremely low radiation values are to be used so that it will be possible to supply the absorption-type cooling plants with water at 95 degrees.
The recooling capacity of 218 kW is adequately designed for the cooling tower of both cooling plants. The possibility of excess pressure in the lines will be avoided by pressure-equalising vessels and additional safety pressure-relief valves.
If building cooling is required, the solar collectors will be used to boost the temperature of the returning heating water. During summertime operation, a total annual plant operating time of 2400 hours has been determined for cooling the building in accordance with the frequency diagram of air enthalpy values in Germany.
On the basis of an average cooling capacity in the daytime of 50 kW, this results in a cooling capacity of 120000 kWh per annum. With an assumed cooling capacity coefficient of 2,5, we calculate an annual electrical power consumption of a comparable compression cooling plant at 48000 kWh per annum. In turn, this means an additional fuel consumption of 145.51 MWh per annum with a power-station efficiency of 33%. With a calorific value of Hw 10 kWh/m3 for natural gas, this would correspond to 14545 m3 n per annum gas consumption. During wintertime operation, a solar collector plant operating time of 960 hours per annum was forecast by computational methods. From this, we calculate a fuel saving of 19200 kWh per annum for the heating plant with an average solar collector plant thermal output of 20 kW, which would correspond to 1920 m3 n less gas consumption for the heating plant per annum.
The overall additional natural gas consumption saved by the solar collector plant is as follows :
Summertime 14545 m3 n per annum
Wintertime 1920 m3 n per annum
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16465 m3 n per annum
This results in a carbon dioxide saving of 31086 kgCO2 per annum.
Programme(s)
Topic(s)
Call for proposal
Data not availableFunding Scheme
DEM - Demonstration contractsCoordinator
51149 KÖLN-PORZ
Germany