Evaluation of suction-line/liquid-line heat exchange in the refrigeration cycle

Abstract

ABSTRAcrThe paper presents a theoretical evaluation of the performance effects resulting from the installation of a liquid line! suction line heat exchanger (llsl·hx). It examines cycle the parameters and refrigerant thermodynamic properties that determine whether the installation results in improvement of COP and volumetric capacity. The study showed that the benefit of application of the Jlsl-hx depends on a combination of operating conditions and fluid properties • heat capacity, latent heat, and coefficient of thermal CJtpansion • with heat capacity being the most influential property. Fluids that perform well in the basic cycle are marginally affected by the llsl-hx, and the impact on the Coefficient of Perfo~mance and volumetric capacity may be either positive or negative. Fluids performing poorly in the basic cycle benefit from the llsl·hx installation through increase of the Coefficient of Performance and volumetric capacity.

Experimental evaluation of an internal heat exchanger in a CO2 subcritical refrigeration cycle with gas-cooler

“…This reduction was mainly Nonetheless, the use of the IHX with a combination of a gas-cooler in the CO cycle, reductions from 1.8 to 3.29 % were measured at -25 ºC of evaporation temperature, but small improvements up to 0.45 % were observed at -40 ºC. 2 Accordingly, it can be concluded that despite the reductions of capacity and COP in the CO subcritical cycle resulted in reductions of the heat to be transferred in the cascade condenser, reductions which were more important at low evaporating levels. This reductions of the heat transferred to the high temperature cycle in cascade systems produced increments on the COP of the cascade system from 0.15 to 2.91 %.…”

“…In the evaporator, the cooling capacity provided by the cycle, Equation (1), was contrasted with the heat transfer rate of the secondary fluid, Equation (2). Their difference in average was of 2.4 % working without IHX and of 3.3 % with IHX.…”

“…Also, the usual criterion to determine the possible advantage of adopting this heat exchanger (Domanski et al [2], Aprea et al [10] and Klein et al [11]) do not offer coherent results for subcritical CO2…”

“…But from the point of view of energy efficiency (COP), its effect can be positive or negative, depending on the considered refrigerant [1]. Using a theoretical approach and neglecting pressure drop, Domanski et al [2] concluded that it is beneficial for refrigerants with high heat capacity. Mastrullo et al [3], considering pressure losses, obtained similar conclusions about the heat capacity, but they added that the IHX is more recommended for refrigerants that provide low COP.…”

The consequently development of refrigerants Chronological assessment

“…While all refrigerants theoretically can reach similar efficiencies with sufficient cycle modification and optimization (Domanski et al, 1994;Domanski, 1995), each element of added complex-ity increases costs, refrigerant charge (amount), the potential for leaks, and thermodynamic irreversibility's and decreases reliability (Calm and Didion, 1997). Hence, refrigerants with high efficiencies in simple cycles have an inherent advantage to improve efficiencies at lower costs and with lower system risk of environmental harm.…”