• Title/Summary/Keyword: Air-side performance

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Cooling Performance Analysis of Ground-Source Heat Pump System with Capacity Control with Outdoor Air Temperature (외기 온도 제어 방식을 적용한 지열 히트펌프 시스템의 냉방 성능 분석)

  • Sohn, Byonghu
    • Journal of the Korean Society for Geothermal and Hydrothermal Energy
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    • v.17 no.4
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    • pp.68-78
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    • 2021
  • In order to solve the increasing deterioration of the energy shortage problem, ground-source heat pump (GSHP) systems have been widely installed. The control method is a significant component for maintaining the long-term performance and for reducing operation cost of GSHP systems. This paper presents the measurement and analysis results of the cooling performance of a GSHP system using capacity control with outdoor air temperature. For this, we installed monitoring equipments including sensors for measuring temperature, flow rate and power consumption, and then monitored operation parameters from July 9, 2021 to October 2, 2021. From measurement results, we analyze the effect of capacity control with outdoor air temperature on the cooling performance of the system. The average performace factor (PF) of the heat pump was 6.95, while the whole system was 5.54 over the measurement period. Because there was no performance data of the existing GSHP system, it was not possible to directly compare the existing control method and the outdoor air temperature method. However, it is expected that the performance of the entire system will be improved by adjusting the temperature of cold water produced by the heat pump, that is, the temperature of cold water on the load side according to the outside air temperature.

Enhancement of Stratification for Solar Water Storage Tank with Spiral Jacket and Coil(Part 2 Simulation) (나선유로에 의한 태양열 축열조 성층화 촉진(제2보 시뮬레이션))

  • Lee, Seong Hoon;Son, Hyo Seok;Hong, Hiki
    • Korean Journal of Air-Conditioning and Refrigeration Engineering
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    • v.26 no.1
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    • pp.8-14
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    • 2014
  • We have performed experiments to enhance the stratification in a storage tank in order to raise the collector efficiency and solar fraction in solar thermal systems. The storage tank with a spiral jacket in the side wall has a scroll-shaped heat exchanger coil added to the upper part. The performance was compared between only the side and upper-side heating part through simulation using TRNSYS under the same weather conditions and initial conditions. As a result, the upper-side heating has a 4.2% advantage in solar fraction, but almost no increase in collector efficiency.

Analysis of Smoke Control According to Jet Fan Location in Straight Long Tunnel (제트 팬 설치 위치에 따른 직선터널 내의 제연해석)

  • Byun, Ju-Suk;Lim, Hyo-Jae;Kang, Shin-Hyung;Lee, Jin-Ho
    • Korean Journal of Air-Conditioning and Refrigeration Engineering
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    • v.19 no.9
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    • pp.662-668
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    • 2007
  • In this study, jet fans are installed with 4 cases in the straight long tunnel; inlet-side setup, middle-side setup, outlet-side setup, and dispersion setup. A bus is selected as fired car, of which fire size is 20MW. And fired car locates at 100m, 700m, 1500m position from tunnel inlet, respectively. FLUENT, commercial finite-volume code, is used to analyze the performance. The velocity profile, $CO_2$ concentration, temperature distribution are examined for analysis. Performance of smoke control is compared by the backlayering length. Consequently, inlet-side setup of jet fans is a little more efficient than other cases considering the fire occurrence frequency in tunnel.

Isolation Performance of the Single-Sided air Curtain in Air-Conditioned Space (공조공간에서 수평토출형 에어커튼의 차단 성능)

  • Sung, Sun-Kyung
    • Korean Journal of Air-Conditioning and Refrigeration Engineering
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    • v.24 no.11
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    • pp.806-812
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    • 2012
  • Air curtains are widely used in commercial and public buildings to replace solid doors where traffic of people is predicted. At doorways where the solid door is open continuously or intermittently, an air curtain may be installed in order to reduce the flow of heat and moisture from the enclosed space to the outside. The purpose of this paper is to predict isolation performance of the single-sided air curtain when the wind is blowing. For the study, a numerical simulation is used to find the influence of various jet velocities on the efficiency of the single-sided air curtain device which is mounted at the side of the doorway. The isolation performance of the single-sided air curtain is evaluated by sealing efficiency which provides the assessment of the infiltration air ratio. According to the result of this study, the single-sided air curtain has lower sealing efficiency than downward-blowing air curtain. Therefore, for energy conservation in heating space, the single-sided air curtain is not recommended because of its low effectiveness.

A Study on the Mechanical Ventilation Design that Consider Supply and Exhaust Efficiency of the Apartment House Kitchen (공동주택 주방의 급ㆍ배기효율을 고려한 기계환기 설계에 관한 연구)

  • 함진식
    • Journal of the Korean housing association
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    • v.15 no.3
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    • pp.101-108
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    • 2004
  • To find more efficient exhaust effect, air curtain of upward or downward trend in gas table and left or right side of range hood were made. As result that film vapor from range hood lower part by digital camera, the air current change by moving existence and nonexistence of exhaust fan and direction of air curtain were known. Under all experiment condition, upward air curtain superior exhaust performance.

Thermal Performance Characteristics of Closed-Wet Cooling Tower (밀폐형 냉각탑의 열성능 특성에 관한 실험적 연구)

  • Sarker, M.M.A.;Kim, E.P.;Moon, C.G.;Yoon, J.I.
    • Journal of Power System Engineering
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    • v.9 no.2
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    • pp.88-92
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    • 2005
  • The experiment of thermal performance about closed-wet cooling tower was conducted in this study. A closed cooling tower is a device similar to a general cooling tower, but with cooling tower replaced by a heat exchanger. The test section for this experiment has the process that the cooling water flows from the top of the heat exchanger to the bottom side in the inner part of the tube, and spray water flows in the gravitational direction in the outer side. Air comes in direct contact with the spray water at the outer side of the tube while passing from the lower the upper part having a counterflow to the spray water. The heat transfer pipe used in this experiment is a bare-type tube having an outer diameter of 15.88mm. The heat exchanger is consisted of seven rows and fifteen columns. In this experiment, thermal performance of the cooling tower is derived from overall heat transfer coefficients between the process fluid and sprayed water and volumetric overall mass transfer coefficient between sprayed water and air.

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A Study of Aerodynamic Characteristics of a Car's Side-view Mirror using CFD (CFD를 이용한 자동차 사이드 미러의 공력특성 연구)

  • Min, Sun-sik;Han, Jun-Kyu;Kwon, Ki Hyun;Choi, Eun-Dong;Kim, Moon-Sang
    • Journal of Aerospace System Engineering
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    • v.2 no.2
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    • pp.46-50
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    • 2008
  • Aerodynamic characteristics, such as drag and lift, play an important role in automobile design under certain speed conditions. Such characteristics are essential to design an automobile since they are directly related to automobile's performance such as passenger safety and fuel consumption. There is a huge demand for the automobile to have safe performance at high speed. Reduction in drag is also important and it could lead to the solution of air flow induced noise and dust problems. The objective of this research is to find out the aerodynamic differences between conventional side mirror and a modified one using CFD. Although drag generated around a side mirror is only about 7% of the total drag when a car runs, it is very closely related to driver's field of vision and noise generation. CFD simulation of the flowfield around a car side-view mirror was performed using a commercial code; Gambit and FLUENT.

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An Experimental Study on the Supplemental Cooling and Heating Performance Using 1 kW Thermoelectric Module for Vehicle (열전모듈을 이용한 자동차용 1 kW급 보조 냉난방 시스템의 성능에 관한 실험적 연구)

  • Lee, Dae-Woong
    • Korean Journal of Air-Conditioning and Refrigeration Engineering
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    • v.26 no.5
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    • pp.224-230
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    • 2014
  • The purpose of this paper is to investigate the performance of supplemental cooling and heating system equipped with the 1 kW thermoelectric module. The system consist of 96 thermoelectric modules, heat sink with louver fin and water cooling jacket which is attached on the hot side of the thermoelectric module. The cooling and heating performance test of the thermoelectric system is conducted with various conditions, such as intake voltage, air inlet temperature, air flow volume, water inlet temperature and water flow rate at calorimeter chamber in consideration of environmental conditions in realistic vehicle drive. The experimental results of a thermoelectric system shows that the cooling capacity and COP is 1.03 kW, and 1.0, and heating capacity and COP is 1.53 kW, and 1.5 respectively.

The Study of Performance Evaluation Coefficient of Fin-and-Tube Heat Exchangers with Frosting (착상을 수반한 핀-관 열교환기의 성능평가계수에 관한 연구)

  • 최봉준;황준현;신종민
    • Korean Journal of Air-Conditioning and Refrigeration Engineering
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    • v.15 no.2
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    • pp.132-136
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    • 2003
  • For the study of performance evaluation on different shape heat exchangers that have the same energy consumption in a refrigerator, we make performance evaluation coefficient (PEC) which can distinguish performance of different shape heat exchangers. The results were reported in order to compare with for the dry frosting and wet frosting test as various definition of PECs. Results showed that PEC of dry frosting test is higher than that of wet frosting test because attached water droplet increases pressure drop of air-side then this decreases performance of heat exchanger.

A Study on Back EMF of BLDC Motor Using Numetical Analysis Method (수치해석 방법을적용한 BLDC 전동기의 역기전력 연구)

  • Kim, Hyun-Cheol
    • Journal of the Korean Society of Safety
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    • v.23 no.4
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    • pp.36-41
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    • 2008
  • This report describes the analytical solution of back EMF for BLDC motor using numerical analysis of air gap flux density. The analysis of air gap flux density is the key to expect the performance of back EMF for the design of brushless motor. The numerical analysis and FEM analysis are performed to vary attachment of stator side or rotor side, radial flux magnetization or parallel flux magnetization, magnet arc angle in the condition of constant air gap. This results have more reliable data comparing with test result of the back EMF for 7 phase BLDC motor.