Floor Radiant System Research Articles

Installation Design and Energy Conservation Analysis of Floor Radiant Cooling/Heating System with Solar Energy

How to reduce the energy consumption of air conditioning, to use new energy such as solar appropriately, and to achieve energy savings, are the problems must be treated in HVAC industry. Because of the high energy consumption of traditional air-conditioning and the need for reduction of emission, an air conditioning system (utilizing solar dehumidifying applied to heating/cooling radiant floor) is designed and installed in this paper. At the same time, as an example, the energy saving potential of system is analyzed. This type of heating/cooling radiant floor system is worth promoted if solve the dehumidification properly. By separating to deal with heat and moisture can reduce the energy-cost of traditional air-conditioning, and to achieve purposes of primary energy saving.

Modeling a radiant floor system with Phase Change Material (PCM) integrated into a building simulation tool: Analysis of a case study of a floor heating system coupled to a heat pump

This work describes a model developed to simulate a radiant floor system with PCM in simple building types. The building simulation model has been validated by comparing its behavior with Energy Plus. The PCM radiant floor model is based on a one-dimensional finite difference scheme where the effective capacity method is used for PCM simulation. Some adjustments have been made to this one-dimensional scheme so that the thermal effect of two-dimensional heat transfer within the radiant floor slab is taken into account.The results of an analyzed case study are also presented in this paper. Here, the PCM floor heating system is fed by a heat pump which mainly operates during night time, thus reducing the costs of electric energy consumption.

Effect of modelling solar radiation on the cooling performance of radiant floors

When modelling buildings, solar radiation has a large impact on the thermal balance because it usually heats the rooms. In radiant systems that are used for heating and cooling buildings, solar radiation has a large influence both on indoor temperatures and on the efficiency of the radiant system. Many analyses have already been carried out in order to study how beam and diffuse radiation can be distributed in a room. One of the most difficult issues, when modelling room thermal balance, is how to simulate the solar radiation when it enters the room, which in turn depends on the reflectance characteristics of the surface finishing elements. In this study, four different radiation models have been applied in order to solve an overall detailed, dynamic thermal balance in a room with pipes embedded in the floor. Two of the models are detailed; the other two consider the radiation entering the room to be diffuse radiation. As for the behaviour of the impinging solar radiation on the covering materials in a room, measurements have been carried out to determine the reflectance coefficients, which will be used in simulations for characteristic materials used in buildings. Results of the simulations show that a simplified model, which considers solar radiation as uniformly distributed in a room, cannot be used for a detailed comfort analysis; however, when looking at the cooling output of a radiant floor system at the design stage, a simplified model can predict energy transfer to a certain level of accuracy. Moreover, results coming from combined measurements and simulations show that the reflectance characteristic of the covering materials does not affect the cooling capacity of the radiant floor systems, since the most important parameter for cooling performance is the thermal conductivity of the covering layer.

Thermal performance of radiant heating floors in furnished enclosed spaces

Abstract The radiant floor heating systems offer distinctive advantages in several special applications and allow to use low temperature heat. A renewed interest has grown in the study of the thermo-physical behaviour of such systems and the influence on health; consequently more accurate design methodologies, taking into account the various relevant parameters, have been developed. However, such methodologies usually refer to “empty spaces” so that working conditions turn out different from those projected. Preliminary theoretical studies [M. Corcione, L. Fontana, G. Moncada Lo Giudice, Riscaldamento a pavimento radiante. Uno studio teorico sul comportamento termico, CDA Condizionamento dell’aria Riscaldamento Refrigerazione 3 (2001) 51–58.] have shown that the presence of furniture in the environment can cause material changes of the system performance and of the operating temperature obtained in the environment. In this paper the thermal performance of radiant floor systems is examined in detail through an experimental study, on a scale model. Experimental measures have been conducted in several conditions of thermal insulation of the enclosed space, of floor covering and outside temperature. For each configuration, tests have been made changing number and typology of the furniture pieces. The furniture influence on the system performance and on the obtained operating temperature has been verified, and the effect of their presence has been evaluated.

A calculation method for the floor surface temperature in radiant floor system

In this paper, a calculation method for the floor surface temperature in radiant floor heating/cooling system is proposed, a new formula is derived to estimate the floor surface temperature. The floor is divided into two layers. The correlation for the thermal conductivity of the lower layer is developed based on the numerical model of the radiant floor system built in this paper. The results show that the floor surface temperature values from the proposed method are in agreement with the experimental and numerical values.

Performance evaluation of a radiant floor cooling system integrated with dehumidified ventilation

The radiant floor cooling system can be used as an alternative to all-air cooling systems, using the existing Ondol system (a radiant floor heating system) in Korea to save energy and maintain indoor thermal comfort. Unfortunately, a radiant floor cooling system may cause condensation on the floor surface under hot and humid conditions during the cooling season. In addition, the radiant floor system does not respond quickly to internal load changes due to the thermal storage effect of the concrete mass, which is usually present in radiant floor cooling systems. This study proposes a radiant floor cooling system integrated with dehumidified ventilation, which cools and dehumidifies the outdoor air entering through the cooling coil in the ventilator by lowering the dew-point temperature to prevent condensation on the floor surface. Furthermore, outdoor reset control was used to modulate the temperature of chilled water supplied to the radiant floor, and indoor temperature feedback control was then used to respond to the internal load changes. To evaluate the performance of the radiant floor cooling system integrated with dehumidified ventilation, both a physical experiment in a laboratory setting and TRNSYS simulation for an apartment in Korea have been conducted. As a result, it was found that the proposed system was not only able to solve the problem of condensation on a floor surface but also to control the indoor thermal environment within the acceptable range of comfort. Furthermore, the proposed system improved the responsiveness to internal load changes.

Comparison of the Performance of a Forced-Air and a Radiant Floor Residential Heating System Connected to Solar Collectors

A detailed building energy analysis tool is used to model the performance of a forced-air system and a radiant floor system. These two systems use a low-temperature tank to store solar energy from a solar collector array. An electrically heated tank at a higher temperature is used to provide any additional heat needed to meet the space heating load. The simulation models developed are then used to compare the performance of the forced-air and radiant floor systems based on maintaining the same operative temperature inside the space. It is found that the portion of the heating load that comes from solar energy is higher in the case of the radiant system. This portion from solar energy increases even further when the operating temperature of the radiant floor is lowered. The results also show that the energy performance of the radiant floor relative to the forced-air system improves for houses with higher envelope R-values and infiltration rates. Given the many different interacting factors that influence the performance of the solar-assisted systems studied, it is very important to use detailed simulation models to help assess which system is more energy efficient for a particular application.

Floor radiant system with heat storage by a solid-solid phase transition material

Abstract Heat storage by means of solid-solid phase transition has been used in a floor radiant system. Tests have been performed in order to establish a comparison between a system storing energy as latent heat with another one using sensible heat. The first system is much more efficient in temperature regulation, allowing an adequate utilization of the off-peak electricity for the charge period. Results obtained in this study show the promising perspectives of the solid-solid phase transition for thermal storage in building materials.