Как выбрать гостиницу для кошек
14 декабря, 2021
In this section, data and performance figures of the system in a typical day of operation are presented. Figure 2 shows on a psychrometric chart the measured air status in the typical cooling and dehumidification process of the system. It has to be noted that the measured values of humidity ratio are affected of errors probably due to the accuracy of the relative humidity transmitters used. For instance, the outlet humidity ratio of the pre-dehumidification coil CC1 is slightly different from the outside air value, even if the coil was set to off. Also the slope of the dehumidification line (1-3) is lower than the enthalpy line, contrarily to the well known thermodynamics of the process.
1 — 2 cooling coil — CC1
2 — 3 dehumidification — DW
3 — 4 HX and infiltration of return air
4 — 5 cooling coil — CC2
5 — 6 building
6 — 7 humidification of return air — HU
7 — 8 heat exchanger — HX
8 — 9 condensation heating coil HC1
9 — 10 solar heating coil HC2
10 -11 regeneration — DW
In addition, the humidity ratio at outlet of the heat exchanger (point 4) is higher than at outlet of the desiccant wheel (point 3), probably due to the air leakages from the return air side to the supply air side. For the considered operation conditions, it was estimated a leakage flow rate of about 18% of the whole return air flow rate. In order to reduce the relevance of leakages into the supply air it will be necessary to improve the air sealing system.
I sol — Solar radiation
P_coll — Solar collectors P_HC 2 — Solar heating coil
T_coll out
T regeneration
4
Figure 3 shows the performance of the solar plant and the regeneration temperature achieved in the heating coil HC 2. It can be noted that the maximum regeneration temperature achieved was 63°C, providing a heating power of 6.4 kW to the regeneration air flow.
In Figure 4 some results related to the regeneration process are presented. It can be noted that the operation of condensation heat recovery coil HC1 is not continuous but intermittent according to the switching on and off of the chiller. The temperature rise up achieved by means of the condensation coil HC1 is in the range of 12-13 °C. The same figure shows the distribution of the heating power for the regeneration by the heat exchanger, the condensation and solar coils (PHX PHCi P HC2 ) and the efficiency of the heat exchanger ranging from 54 to 70%.
P CC2 — Cooling coil P DEC — Desiccant cooling P CC1 — Pre-dehumidification coil
——— x set point supply
x supply —•— T supply
——— T set point supply
— — x ext — Outside humidity ratio T ext — Outside temperature
Fig. 5. Cooling power of desiccant cooling cycle and auxiliary cooling coils — date: 25.07.2008