Effect of Different Zigzag Channel Shapes of PCHEs on Heat Transfer Performance of Supercritical LNG

Abstract

The channels of a printed circuit heat exchanger (PCHE) can have different shapes, and the zigzag channel shape is one of the most widely used because of the relatively simple manufacturing process and low cost. However, the heat transfer enhancement of a zigzag channel is at the expense of increasing the pressure drop. In this paper, new channel shapes of a PCHE, i.e., a zigzag with an inserted straight channel and a zigzag channel with radian, were numerically investigated, with the aim of improving the heat transfer and reducing the pressure drop of supercritical LNG using the SST κ-ω model. The local and total pressure drop and heat transfer performance of supercritical LNG in a zigzag channel, zigzags with 1–5 mm inserted straight channels, and a zigzag channel with radian were analyzed by varying the mass flow rate from 1.83 × 10−4 to 5.49 × 10−4 kg/s. Performance evaluation criteria (PEC) were applied to compare the overall heat transfer performance of the zigzags with 1–5 mm inserted straight channels and a zigzag channel with radian to the zigzag channel of a PCHE. The maximum pressure drop for the zigzag channel was twice the minimum pressure drop for the zigzag channel with radian, while the convective heat transfer coefficient of the zigzag with a 4 mm inserted straight channel was higher, which was 1.2 times that of the zigzag channel with radian with the smallest convective heat transfer coefficient. The maximum value of the PEC with 1.099 occurred at a mass flow rate of 1.83 × 10−4 kg/s for the zigzag with a 4 mm inserted straight channel, while the minimum value of the PEC with 1.021 occurred at a mass flow rate of 5.49 × 10−4 kg/s for the zigzag with a 1 mm inserted straight channel. The zigzag with a 4 mm inserted straight channel had the best performance, as it had a higher PEC value at lower mass flow rates.

Performance and Exergy Transfer Analysis of Heat Exchangers with Graphene Nanofluids in Seawater Source Marine Heat Pump System

“…There are many analysis and evaluation methods currently used to measure the energy consumption of heat exchangers and guide their optimal design [19]. They can be divided into the following three categories: first, the analysis and evaluation based on the first law of thermodynamics [20]; second, the evaluation combining the conservation of energy and the second law of thermodynamics [21]; finally, the above methods are improved and derived, including thermoeconomics [22], composition method [23], the theory of fire accumulation dissipation [24], etc. Sun et al [25] studied a shell-and-tube heat exchanger with inclined three-lobed baffles, numerically simulated its flow and heat transfer characteristics, and analyzed the structure using heat transfer coefficients and pressure drops.…”

Experimental and Numerical Analysis of Condensation Heat Transfer and Pressure Drop of Refrigerant R22 in Minichannels of a Printed Circuit Heat Exchanger

“…Here, the flow process of the R22 and the heat transfer process with supercritical nitrogen inside the PCHE minichannels are researched under different superheated, saturated, and two-phase inlet conditions through experiments and numerical simulations, respectively. The research in this paper is a continuation of previous research [20][21][22][23][24]. This research is to provide basics and references for the next step in the study of the flow and heat transfer performance of LNG and propane in PCHEs in practical applications.…”

“…Regarding the field of regasification of cryogenic fluids, Zhao et al, [20] analyzed the flow and heat transfer performance of supercritical nitrogen in the PCHE straight channels via numerical simulations and discussed the influence of the inlet pressure and mass flow rate for the heat exchange and flow performance. Zhao et al, [21,22] studied the effect of PCHE zigzag channels with different shapes and angles on the heat transfer performance and thermal-hydraulic characteristics of supercritical LNG through numerical simulation. Due to the flammability and explosive nature of LNG, during the experiment liquid nitrogen often is used rather than LNG to test PCHE performance.…”

Heat transfer performance comparison of printed circuit heat exchangers with straight, zigzag and serpentine flow channels for waste heat recovery

“…The latter resulted in an energy consumption increase with the pressure drop and consequently reduced the efficiency of the system. Applying the performance evaluation criteria (PEC) for a heat exchanger, which is the ratio of Nusselt number to friction factor, Zhao et al 25 inserted the truncation of right‐angle channel bends with straight diagonals and curved bends, creating the better performance. Based on the entropy and exergy evaluation, Yilmaz et al 26 investigated the efficiency of heat transfer performance.…”