IEA Solar Heating and Cooling Programm - NachhaltigWirtschaften.at

IEA SHC Task 38 Solar Air Conditioning and Refrigeration Subtask A Report, Date: November 2010
In the first three charts the cooling-, driving- and recooling power is drafted together with the
linked supply- and return temperatures. In the beginning the chiller shows a clocking
behavior, starting three times before running in a stable condition. The reason for switching
on and off is the insufficient useable heat quantity (with a temperature base over 63°C) in the
hot storage. At approximately 12:30 p.m. the incoming solar yield reaches sufficient values to
keep the machine running. The solar plant is designed for a low flow configuration in order to
assist the space heating of the house in winter times. This has certain disadvantages
concerning the cooling mode. On this day the chiller has an average power share of around
6/10/16 kW (cooling/driving/recooling). For recooling the stable chiller inlet temperature
values of approximately 22°C were reached. The heat rejection system is working well
throughout the day. Furthermore the driving heat inlet temperature of the absorption chiller
reaches an average value of 69°C for the day.
In the beginning the cooling outlet temperature towards the core activation shows stable
values of approximately 19°C. At around 14:00 p.m. the flow and return temperature drops
rapidly down to a value of 5°C. After a fast temper ature rising up to 18°C the same
characteristic temperature drop repeats two times. A reason for the temperature drop could
be the closing of the regulation valve V b correlating with a domestic hot water priority
function. If the valve is closed the chiller cools down in its short closed cycle as far as
possible until the valve opens again.
These low cooling temperatures affect thermal performance of the chiller. In Figure 10 the
thermal COP during September 5, 2009 is shown. The bad performance can be identified
exactly at the same time, when the cooling temperature drops down. Due to an internal
ammonia storage inside the chiller there are some peaks in those periods, where the COP
exceeds the value of 0.8. Generally the Pink absorption chiller handles the rough operating
conditions quite well and balances some of the outside influences.
Figure 10: Thermal COP of the Pink chiller on September 5, 2009
Thermal and electrical COPs for the period between August 21, 2009 and the end of
September are shown in Figure 11. An average thermal COP for that period of 0.57 could be
reached. Electrical COPs range in daily values from 0.5 to 5 and achieve an average value of
3.1. In the period between the September 11 and 18, 2009 no results were monitored due to
a data processing problem of the external operator station.
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