ANSI Standard Z21.13 tests and rates condensing boiler performance with an 80[degrees]F (27[degrees]C) boiler entering water temperature
(EWT) and a 100[degrees]F (55[degrees]C) temperature rise (delta-T) to produce a boiler leaving water temperature (LWT) of 180[degrees]F (82[degrees]C).
Step V: At time t, measure [[??].sub.w,f], [T.sub.EWT,f], [T.sub.LWT,f], [p.sub.sat,r,f, and [[??].sub.ref],f] and verify that the entering water temperature
to the test BPHE in fouled and clean condition is the same; that is, [T.sub.EWT,f] - [T.sub.EWT,c] < 0.1 [degrees]F (0.05[degrees]C).
Minimum entering water temperature
was above 32[degrees]F (0[degrees]C) during the heating season and below 67[degrees]F (19.4[degrees]C) during cooling season (Figure 5).
On the other hand, calculated entering water temperature
could also be used as parameter in control strategy.
Figure A1 shows the surface produced by water-side fouling given the high entering air temperature and low entering water temperature
used in Table A1, 32[degrees]C and 7[degrees]C (89.6[degrees]F and 44.6[degrees]F), respectively.
Figure 1 above Illustrates the negative impact of rising heat pump entering water temperature
upon geothermal heat pump cooling efficiency.
[t.sub.EWT] Entering water temperature
Table 2 shows coil selections for a number of cities and the entering water temperature
required to meet the supply air temperature setpoint established in Table 1.
Other variables such as the condenser entering water temperature
, chilled water leaving temperature, outdoor air dry bulb and wet bulb temperatures are also collected from the software output along with the hourly cooling load.
The tower is selected for 3 gpm/ton (0.05 mL/J) and an entering water temperature
of 95[degrees]F (35[degrees]C) at design conditions.
For the tests shown, the entering water temperature
was set to 14[degrees]C (58[degrees]F).
Chiller Capacity (tons) 500 Cooling Tower (Condenser) Flow Rate (gpm) 1000 Chiller Efficiency (COP) 6.10 Design Wet Bulb ([degrees]F) 78 Design Approach Temperature ([degrees]F) 4.5 Tower Entering Water Temperature
([degrees]F) 96.5 Tower Leaving Water Temperature ([degrees]F) 82.5 Design Range (Condenser Water [DELTA]T) ([degrees]F) 14 TABLE 2 Cooling tower approach temperature at 60[degrees]F wet-bulb temperature.