Temperature efficiency of heat exchangers in air handling units

Michalak, Piotr; Grygierczyk, S.

doi:10.30464/jmee.2019.3.3.267

Cited by 6 publications

(7 citation statements)

References 19 publications

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“…Five air handling units (AHUs), one per each storey, were used. Four of them, serving office rooms, conference rooms and social rooms, are equipped with rotary heat exchangers and one, mainly for sanitary facilities and utility rooms, is with cross-flow exchanger [54,55]. The building management system (BMS) integrates management of installations and controls the operating parameters of individual devices.…”

Section: Case Objectmentioning

confidence: 99%

“…But this analysis also covered unoccupied periods. In the considered buildings the TABS system works permanently and is supported during working periods by mechanical ventilation with heat recovery [55]. This irregular operation of the HVAC system affects internal thermal conditions.…”

Section: Vertical Temperature Profilementioning

confidence: 99%

“…During the cooling period at the beginning of a working day air temperature is stable ( Figure 23a). It begins to decrease when the ventilation is on and fresh outdoor air starts to cool down the indoor air [55]. This situation changes with office opening hour when internal heat gains occur from occupants and equipment resulting in rising indoor air temperature.…”

Section: Thermal Performance Of the Tabsmentioning

confidence: 99%

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Selected Aspects of Indoor Climate in a Passive Office Building with a Thermally Activated Building System: A Case Study from Poland

Michalak

2021

Energies

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Modern buildings with new heating, ventilation and air conditioning (HVAC) systems offer possibility to fit parameters of the indoor environment to the occupants’ requirements. The present paper describes the results of measurements performed in an office room in the first Polish passive commercial office building during four months of normal operation. They were used to calculate parameters describing thermal comfort: vertical air temperature profile, floor surface temperature, predicted mean vote (PMV) and predicted percent of dissatisfied (PPD). Obtained results confirmed good thermal conditions in the analysed room. The average temperature of the floor’s surface varied from 20.6 °C to 26.2 °C. The average vertical air temperature, calculated for working days, was from 22.5 °C to 23.1 °C. The temperature difference between the floor and 5 cm below the ceiling was from −0.9 °C to 6.3 °C. The PMV index varied from 0.52 to 1.50 indicating ‘slightly warm’ sensation, in spite of ‘neutral’ reported by employees. Also measured cooling and heating energy consumption was presented. The performed measurements confirmed the ability of thermally activated building system (TABS) to keep good thermal conditions.

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Section: Case Objectmentioning

confidence: 99%

Section: Vertical Temperature Profilementioning

confidence: 99%

Section: Thermal Performance Of the Tabsmentioning

confidence: 99%

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Selected Aspects of Indoor Climate in a Passive Office Building with a Thermally Activated Building System: A Case Study from Poland

Michalak

2021

Energies

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“…It consists of air filters (1), exhaust fan (2), cross-flow heat exchanger (3), supply fan (4), heating coil (5), and cooling coil (6). Temperatures in Figure 1 are assigned according to EN 308 [46,50], which specifies methods to be used for laboratory testing of air-to-air heat recovery devices in buildings to obtain rating data and verify performance data given by manufacturers.…”

Section: Air Handling Unitmentioning

confidence: 99%

Annual Energy Performance of an Air Handling Unit with a Cross-Flow Heat Exchanger

Michalak¹

2021

Energies

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Heat recovery from ventilation air is proven technology resulting in significant energy savings in modern buildings. The article presents an energy analysis of an air handling unit with a cross-flow heat exchanger in an office building in Poland. Measurements were taken during one year of operation, from 1 August 15 to 31 July 16, covering both heating and cooling periods. Calculated annual temperature efficiency of heat and cold recovery amounted to 65.2% and 64.6%, respectively, compared to the value of 59.5% quoted by the manufacturer. Monthly efficiency of heat recovery was from 37.6% in August to 68.7% in November, with 63.9% on average compared to 59.5% declared by the manufacturer. Cold recovery was from 63.3% in April to 72.8% in September, with 68.1% annually. Calculated recovered heat and cold amounted 25.6 MWh and 0.26 MWh, respectively. Net energy savings varied from −0.46 kWh/m2 in August, when consumption by fans exceeded savings, to 5.60 kWh/m2 in January.

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“…Also significant changes in input values (outdoor temperature, ventilation rate, etc.) may occur between subsequent time steps [20][21][22][23]. These factors influence calculated instantaneous indoor temperature and thermal power required to maintain set point temperature.…”

Section: Introductionmentioning

confidence: 99%

Thermal - electrical analogy in dynamic simulations of buildings: Comparison of four numerical solution methods

Michalak

2020

Journal of Mechanical and Energy Engineering

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The lumped capacitance method is widely used in dynamic modelling of buildings. Models differ in complexity, solution methods and ability to simulate transient behaviour of described objects. The paper presents a mathematical description of a simple 1R1C thermal network model of a building zone. Four numerical methods were applied to solve differential equation describing its dynamics. For validation purposes two test cases (600 and 900) from the BESTEST procedure were used. In both cases detailed results were given. Better ability of the simulation model to reproduce transient behaviour of the modelled buildings was noticed in case of the lightweight object (case 600). Annual heating and cooling demand was within the reference range for heavyweight one (case 900). The kind of the computation method had no significant effect on simulation results.

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Temperature efficiency of heat exchangers in air handling units

Cited by 6 publications

References 19 publications

Selected Aspects of Indoor Climate in a Passive Office Building with a Thermally Activated Building System: A Case Study from Poland

Selected Aspects of Indoor Climate in a Passive Office Building with a Thermally Activated Building System: A Case Study from Poland

Annual Energy Performance of an Air Handling Unit with a Cross-Flow Heat Exchanger

Thermal - electrical analogy in dynamic simulations of buildings: Comparison of four numerical solution methods

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