scholarly journals Experimental Study on Thermal Response Characteristics of Indoor Environment with Modular Radiant Cooling System

Energies ◽  
2020 ◽  
Vol 13 (19) ◽  
pp. 5012
Author(s):  
Zhengrong Li ◽  
Dongkai Zhang ◽  
Cui Li
Keyword(s):  
Water Temperature ◽  
Indoor Air ◽  
Indoor Environment ◽  
Cooling System ◽  
Thermal Response ◽  
Low Energy ◽  
Response Characteristics ◽  
Radiant Cooling ◽  
Low Energy Buildings ◽  
Supply Water

The radiant cooling system has a substantial energy-saving effect and can be widely applied in different kinds of low-energy buildings. This article reports the experimental study of the design strategy of the radiant cooling system in low-energy buildings from the perspective of thermal response characteristics of an indoor environment. Two types of a modular radiant cooling system, namely, the copper tube radiant cooling (CTRC) and the capillary radiant cooling (CRC) systems, were investigated. The experiments were conducted in two office rooms characterized by low energy consumption. In total, 16 cases (eight for CTRC and eight for CRC) were analyzed, covering supply water temperature with a range of 12–19 °C. The experimental results show that the supply water temperature has a more substantial effect on the temperature distribution of the envelope for CTRC, than that of CRC. The indoor air temperature stratification is acceptable in the active area of the occupant with a modular radiant cooling system. Moreover, the thermal response of the envelope is highly sensitive to the lower supply water temperature (below 16 °C) using CTRC and to the higher supply water temperature (above 15 °C) using CRC. The low supply water temperature (below 15 °C) can improve the thermal stability speed of indoor air to a greater degree using CTRC, than that of CRC. The supply water temperature for CTRC with 15–16 °C, and 18–19 °C for CRC in low-energy buildings can exert an optimal cooling benefit.

scholarly journals Experimental study on the dynamic thermal response of a radiant floor system in an office building

2021 ◽  
Vol 246 ◽  
pp. 10003
Author(s):  
Jing Ren ◽  
Meng Su ◽  
Xintian Zhao ◽  
Jiying Liu ◽  
Shoujie Song
Keyword(s):  
Water Temperature ◽  
Thermal Performance ◽  
Cooling System ◽  
Dynamic Change ◽  
Thermal Response ◽  
Characteristic Parameter ◽  
Intermittent Control ◽  
Cooling Mode ◽  
Floor System ◽  
Supply Water

The dynamic thermal performance of radiant terminal plays an important role in the design and control of radiant cooling system, which is shown as the dynamic thermal response of radiant floor system (RFS) under imposed control. In this paper, the field measurement method was used to study the dynamic thermal response of RFS. The RFS was activated in summer and the supply water temperature was regulated in winter to make dynamic change of thermal performance. The floor surface temperature was selected as the characteristic parameter to describe the dynamic heat transfer performance of the system, and response time τ95 and time constant τ63 were used to quantify the dynamic thermal response. The maximum τ95 was 13.5 h and τ95/τ63 was greater than or equal to 2 in the cooling mode, while τ95 and τ63 were both less than 10 h and τ95/τ63 was 1.6 in the heating mode. As a result, there was no significant lessening of temperature change rate, and the thermal response of RFS was faster under intermittent control of supply water temperature in winter. Therefore, the study aims at providing reference for making intermittent control strategy by using the dynamic thermal performance of radiant system.

scholarly journals Indoor Air Quality Campaign in an Occupied Low-Energy House with a High Level of Spatial and Temporal Discretization

2021 ◽  
Vol 11 (24) ◽  
pp. 11789
Author(s):  
Najwa Kanama ◽  
Michel Ondarts ◽  
Gaëlle Guyot ◽  
Jonathan Outin ◽  
Evelyne Gonze
Keyword(s):  
Air Quality ◽  
Indoor Air Quality ◽  
Indoor Air ◽  
Low Cost ◽  
Weather Conditions ◽  
Low Energy ◽  
Health Impacts ◽  
Cumulative Exposure ◽  
Temporal Discretization ◽  
Low Energy Buildings

Background and gaps. The topic of indoor air quality (IAQ) in low-energy buildings has received increasing interest over the past few years. Often based on two measurement points and on passive measurements over one week, IAQ studies are struggling to allow the calculation of pollutants exposure. Objectives. We would like to improve the evaluation of the health impacts, through measurements able to estimate the exposure of the occupants. Methodology. This article presents detailed IAQ measurements taken in an energy-efficient occupied house in France. Two campaigns were conducted in winter and spring. Total volatile organic compounds (TVOC), formaldehyde, the particle numbers and PM2.5, carbon dioxide (CO2), relative humidity (RH), temperature (T), ventilation airflows, and weather conditions were dynamically measured in several points. Laboratory and low-cost devices were used, and an inter-comparison was carried out for them. A survey was conducted to record all the daily activities of the inhabitants. IAQ performance indicators based on the different pollutants were calculated. Results. PM2.5 cumulative exposure did not exceed the threshold available in the literature. Formaldehyde concentrations were high, in the kitchen, where the average concentrations exceeded the threshold. However, the formaldehyde cumulative exposure of the occupants did not exceed the threshold. TVOC concentrations were found to reach the threshold. With these measurements performed with high spatial and temporal discretization, we showed that such detailed data allow for a better-quality health impacts assessment and for a better understanding of the transport of pollutants between rooms.

scholarly journals Indoor air quality of newly built low-energy preschools – Are chemical emissions reduced in houses with eco-labelled building materials?

2018 ◽  
Vol 28 (4) ◽  
pp. 506-519 ◽  
Author(s):  
Josefin Persson ◽  
Thanh Wang ◽  
Jessika Hagberg
Keyword(s):  
Air Quality ◽  
Relative Humidity ◽  
Indoor Air Quality ◽  
Air Temperature ◽  
Indoor Air ◽  
Building Materials ◽  
Ventilation System ◽  
Sampling Period ◽  
Low Energy ◽  
Low Energy Buildings

The use of an airtight frame in low-energy buildings could increase the risk of health-related problems, such as allergies and sick building syndromes (SBS), associated with chemical emissions from building materials, especially if the ventilation system is not functioning properly. In this study, the indoor air quality (IAQ) was investigated in newly built low-energy and conventional preschools by monitoring the indoor air temperature, relative humidity, particle-size distribution and levels of carbon dioxide (CO2), nitrogen dioxide (NO2), formaldehyde and total volatile organic compounds (TVOC). The thermal comfort was satisfactory in all preschools, with average indoor air temperature and a relative humidity at 21.4°C and 36%, respectively. The highest levels of TVOC (range: 130–1650 µg/m3 toluene equivalents) and formaldehyde (range: 1.9–28.8 µg/m3) occurred during the first sampling period associated with strong emissions from building materials. However, those preschools constructed with environmental friendly building materials (such as Swan Eco-label) had lower initial TVOC levels compared to those preschools constructed with conventional building materials. The IAQ and indoor chemical emissions were also strongly dependent on the functioning of the ventilation system. Preliminary risk assessment indicated that exposure to acrolein and crotonaldehyde might lead to respiratory-tract irritation among occupants.

Performance assessment of earth pipe cooling system for low energy buildings in a subtropical climate

2015 ◽  
Vol 106 ◽  
pp. 815-825 ◽  
Author(s):  
S.F. Ahmed ◽  
M.M.K. Khan ◽  
M.T.O. Amanullah ◽  
M.G. Rasul ◽  
N.M.S. Hassan
Keyword(s):  
Performance Assessment ◽  
Cooling System ◽  
Low Energy ◽  
Subtropical Climate ◽  
Low Energy Buildings

scholarly journals Optimal control of secondary side supply water temperature for substation in district heating systems

2019 ◽  
Vol 111 ◽  
pp. 06015
Author(s):  
Juan Hou ◽  
Haoran Li ◽  
Natasa Nord
Keyword(s):  
Water Temperature ◽  
Air Temperature ◽  
Temperature Control ◽  
Reference Values ◽  
Indoor Air ◽  
District Heating ◽  
Dynamic Information ◽  
Heating Systems ◽  
District Heating Systems ◽  
Supply Water

Low temperature is the most significant feature of the future district heating system- the 4th generation district heating (4GDH). However, a widely used control strategy for supply water temperature in substation is weather- compensated control. It is a feedforward control without any dynamic information about buildings, which can lead to higher or lower supply water temperature. This paper presents model predictive controller (MPC) applied to the supply water temperature control for substations in district heating systems. MPC is an advanced control technique, which can make full use of dynamic information of buildings to determine the optimal supply water temperature of substations. In this paper, a multiple inputs and single output dynamic model was identified by subspace methods. Two different MPC controllers were designed in Simulink. The MPC controller 1 focused on keeping indoor air temperature at reference values. The MPC controller 2 focused on both keeping indoor air temperature at reference values and tracking the minimum supply water temperature in order to find the temperature potential for the future DH systems. Both of the MPC controllers proved to have a better tracking effect for indoor air temperature and lower average supply temperatures compared to weather- compensated. The MPC controller 2 could further lower supply water temperature compared to the MPC controller 1 by tracking minimum supply water temperature in its objective function. The average supply water temperatures for the weather- compensated, the MPC controller1, and the MPC controller 2 were 52°C, 51°C and 50°C, respectively. The results showed that MPC has a great potential in the area of supply water temperature control of the district heating systems.

Sign in / Sign up

Export Citation Format

Share Document