From Figs.3 to 5 show the example simulation results for the simulation case of the collector area 30m2 and the storage tank volume 2.0m3 using the Case A DHW supply.

Fig.3 shows the simulation results of the solar DHW system from 18th to 20th in January as the example of typical days in winter. A collector efficiency exceeds 70% in the midday of 18th, a clear day. The water temperature defference at

 

Collector efficiency

 

•/""N

 

0

 

outlet

 

nlet

 

-1(top)

the inlet and outlet of the collector is 8.9 degrees C. The water temperature in the storage tank becomes 40 degrees C in the clear day. The temperature stratification is seen in storage tank when DHW is supplied in the afternoon, and the water temperature in the storage tank falls slowly. The maximum water temperature of the storage tank is 28 degrees C in January 19th, a cloudy day.

Fig.4 shows the simulation results of the

Fig.5 Hourly simulation results in summer days (collector area 30m2 solar DHW system from

and storage tank volume 2.0m3 with Case A DHW supply, A30V2.0). 22nd to 24th in May as

the example of typical

days in spring. The water temperature of the top in the storage tank rises to nearly 60 degrees C in the afternoon of the clear days in May 23rd and 24th. On May 22nd, a cloudy day, the maximum water temperature in the storage tank is 38 degrees C. The solar energy supplies a half of DHW heat load in the afternoon of the clear days.

Fig.5 shows the simulation results of the solar DHW system from 7th to 9th in August as the example of typical days in summer. As shown Table 2, smaller DHW supply rate was used in summer. As the water temperature in the storage tank exceeds 60 degrees C from 12:00 to 24:00 of August 8th and 9th, the DHW heat load is completely covered by the solar energy in this time.