Как выбрать гостиницу для кошек
14 декабря, 2021
The results obtained for the different simulations are summarised in the tables 1 and 2. They show the required solar collector surface to achieve the objective of 700 MWh/year of chilled water and
different energy performance parameters for the different thermal chiller and solar thermal technologies.
As expected, both tables show that solar collectors having higher efficiency parameters give a higher heating and cooling production per area unit. Also it could be observed that because of the lower operation of the solar adsorption systems, these have higher solar gain coefficients than the absorption ones. Alternatively, the specific chilled energy coefficients depends not only of the collector technology but also of the thermal chiller technology, being the best options the ab/adsorption systems with ETC-CPC collector with a maximum performance of 606 kWh/m2y for the combination with the BDH-65 chiller. The adsorption systems specific chilled energy coefficients only exceed the ones of the absorption systems when FPC collectors are used.
Comparing the Broad solar cooling systems themselves, the BDH-65 systems give a better performance than the BDH-50 ones, especially for ETC and FPC collectors. That fact leads to lower solar collector surface requirement to achieve the 700 MWh of chilled energy. The reason of that behaviour is the better annual average performance of the thermal collectors in BDH-65 systems. Looking at only to the adsorption results of table 2, the MYCOM ADR-60 SYSTEMS present better performance than the ADR-80. In that case the solar system has more or less the same performance and the explanation of this result is that the ADR-60 systems operate at slight higher temperatures in the generators-receivers, obtaining then slight higher values of their COP.
T able 1. Collector surface and energy performance parameters for different solar collector technologies and absorption chillers.
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Table 2. Collector surface and energy performance parameters for different solar collector technologies and adsorption chillers.
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Comparing this analysis to the previous study [3], it could be observed that the MYCOM ADR-80 results are very similar with differences lower than 3.5 %. In the previous study we used some empirical correlations to simulate that chiller. This entire means that the method suggested by Ktihn and al. [3] is valid to model this adsorption chiller. As regards the absorption chiller model, in [3] we used the Thermax LT 21 S with 739 kW with an average COP of 0.64. In the case we are dealing with now we selected the Broad chillers because they present a better COP (0.76). As a consequence, the values of the specific chiller capacity calculated now are between a 4 and 15 % higher. Obviously, the collectors’ surface requirements are also reduced in the same amount.
It should be remarked that, due to the special chilled water demand profile, the solar cooling system should be in operation the whole year. As a result the cooling water temperature is almost 2/3 of the year close to 22 °C. One of the most important consequences of working at lower cooling tower water temperatures is that the temperatures needed in the generator of the chiller could be lowered maintaining the capacity and then increasing the performance of the solar thermal field. In fact, the temperature in the generator can be as low as 60°C for adsorption and 85°C for absorption in the winter period.