22 May 2008

COABSORBENT HEAT PUMPS


Heat pumps based on the coabsorbent cycles, recently introduced by the author, may
be a feasible challenge for the classic mechanical vapour compression heat pumps, because of
at least two main characteristics of coabsorbent technology: a) it has the capacity to process
depleted heat/sink sources having a small temperature gap between them (e.g. 15-40), due to a
particular technique, that of truncation, and b) given that classic condensing absorption
technology is a particular case of the coabsorbent one, it is versatile, offering a broad technical
solutions portfolio to a given application, which range from highest efficiency + highest
complexity to lowest efficiency + most reduced complexity of a heat pump. First, a short
introduction of the coabsorbent cycles is outlined, with emphasis of the truncated coabsorbent
cycles and of the heat pumps based on the heating fractals, operated in an absorption and
hybrid mode. Out of all coabsorbent heat pump cycles analysed, three applications have been
promoted for this work: a) nontruncated hybrid, b) simple truncated hybrid and c) quadruple
truncated, respectively, in connection with heat/sink sources coming of naturally (underground
water/ambient air), or industrially (Steam Rankine Cycle (SRC) and Organic Rankine Cycle
(ORC) related). Generally, the heat pumps COP and capacity depend on truncation columns
complexity in such a way that the higher the complexity, the higher the COP, but the lower the
capacity. Their COP depend on temperature lift and gap and generally increase with truncation
column high increase from several times to one and two magnitude orders as compared to
mechanical vapour compression existing heat pumps COP. Heat (depleted) source use
effectiveness, E, is smaller than that of a mechanical vapour compression existing heat pump,
ranging from about 24 to 47 percent for c) to a) applications, in absorption working mode, and
from about 30 to about 70 percent in the hybrid working mode.