Thermal Performance and Energy Saving Analysis of Indoor Air–Water Heat Exchanger Based on Micro Heat Pipe Array for Data Center

Abstract

According to the temperature regulations and high energy consumption of air conditioning (AC) system in data centers (DCs), natural cold energy becomes the focus of energy saving in data center in winter and transition season. A new type of air–water heat exchanger (AWHE) for the indoor side of DCs was designed to use natural cold energy in order to reduce the power consumption of AC. The AWHE applied micro-heat pipe arrays (MHPAs) with serrated fins on its surface to enhance heat transfer. The performance of MHPA-AWHE for different inlet water temperatures, water and air flow rates was investigated, respectively. The results showed that the maximum efficiency of the heat exchanger was 81.4% by using the effectiveness number of transfer units (ε-NTU) method. When the max air flow rate was 3000 m3/h and the water inlet temperature was 5 °C, the maximum heat transfer rate was 9.29 kW. The maximum pressure drop of the air side and water side were 339.8 Pa and 8.86 kPa, respectively. The comprehensive evaluation index j/f1/2 of the MHPA-AWHE increased by 10.8% compared to the plate–fin heat exchanger with louvered fins. The energy saving characteristics of an example DCs in Beijing was analyzed, and when the air flow rate was 2500 m3/h and the number of MHPA-AWHE modules was five, the minimum payback period of the MHPA-AWHE system was 2.3 years, which was the shortest and the most economical recorded. The maximum comprehensive energy efficiency ratio (EER) of the system after the transformation was 21.8, the electric power reduced by 28.3% compared to the system before the transformation, and the control strategy was carried out. The comprehensive performance provides a reference for MHPA-AWHE application in data centers.

Analysis of the Efficiency of Using Heat Exchangers with Porous Inserts in Heat and Gas Supply Systems

“…Thus, the unit included two circuits: one for water circulation, the other for freon circulation. The first circuit with water was equipped with pump (4), boiler (5) for heating water, and control and measuring device (6), which makes it possible to track the change in water temperature over time and monitor the mass flow rate. The freon circuit is created using the principle of a refrigeration unit and is equipped with compressor (7), condenser (8), receiver (9), a moisture-separating filter, (10) and a throttle (12).…”

“…One of the promising ways to increase the intensity of heat transfer is the use of various designs of heat exchangers [4][5][6] and modern materials in them [7][8][9], for example, porous metals [10,11].…”

Monitoring of Thermal and Flow Processes in the Two-Phase Spray-Ejector Condenser for Thermal Power Plant Applications

“…From Equation (40) for the DN50 diameter, we obtain: ∆p 50/ξ min = 14 Pa, ∆p 50/ξ max = 2299 Pa. The change of direction at an angle of 90 • in the system will take place n = 3 times, then the total minor losses.…”

“…Using the propagation model of uncertainty [37][38][39][40][41], the standard combined uncertainty u c of y can be calculated from the formula:…”

Calculating the Efficiency of Complex-Shaped Fins

“…Bošnjaković et al [2] compare the analytical and numerical methods for annular fins. Jing et al [3] used the calculation of the fin efficiency of a serrated type of finned surface for more complicated research on the air-water heat exchanger for the data center. Nakhchi et al [4] used the calculation of the effectiveness of stepped fins' area on the performance improvement of phase change thermal energy storage.…”