heat exchanger

Ventilation in buildings dilutes the indoor air pollutants by replacing part of the air with outdoor air to guarantee an adequate indoor air quality (IAQ). In heating-dominated climates, the exchanged air has a lower mean temperature than the indoor air, which leads to a surplus heating demand in the building. A heat exchanger recovers part of the heat from the expelled air, contributing to the reduction of the extra heating demand. Smart ventilation systems work with reduced airflows, without compromising the IAQ and lowering the heating demand.

In this paper a new ventilated window with a PCM heat exchanger is proposed. In winter, the heat exchanger works as a solar collector to store heat for pre-heating of the ventilated air. In summer, it works in cooperate with night ventilation to pre-cool the ventilated air. In this work, the prototype of the heat exchanger is built and tested experimentally. The PCM heat capacity measured by differential scanning calorimetry DSC is used to help understand the phase change processes. The PCM temperature at different heights in both melting and freezing processes is measured.

Mr.Platts briefly reviews current Canadian housing and the potential for controlled ventilation with exhaust air heat recovery. Discusses cost effectiveness of exhaust air heat recovery and suggests that payback periods are generally too long and hence uneconomic. Mr.Bonnyman discusses the market for domestic heat recovery units. Briefly reviews the types of heat recovery equipment. Gives product information for units available in Canada.

This paper explores the simulation of the thermal performance of a radiant floor for heating and cooling that is connected with an underground heat exchanger installed under the concrete floor of a house. In the heating season, an electric boiler is used to maintain the operative temperature at the set point value by varying the supply water temperature to the radiant slab. In the cooling season, the water from the radiant floor is circulated through an underground heat exchanger installed under the concrete slab.

LBNL - Proceedings of Indoor Air 2002 (9th International Conference on Indoor Air Quality and Climate) - June 30 - July 5, 2002 - Monterey, California - vol 1, pp 521-526, 3 figs, 10 refs","This paper presents a model for particle deposition on fin-and-tube heat exchangers, that takes into account mechanisms such as impaction, diffusion, gravitational settling and turbulence. Models results are presented and analysed. They agree with experimental data.

The effectiveness of natural ventilation, i.e. its ability to ensure indoor air quality and passive cooling ina building, depends greatly on the design process.

A municipality water reticulation R22 ground-coupled reversible heat pump, was investigated as an alternative to conventional air source systems. The investigation was conducted by developing analytical models that were used for the design of a ground-coupled reversible heat pump and a conventional, also reversible air-to-air system. The models were verified with a commercially available computer program as well as with measurements on the two systems.

This paper describes a study on the performance evaluation of a hybrid ventilation systemwith a heat exchanger. This system has two passive stacks and a heat exchange unit, which includes a heat exchange element, a supply fan, an exhaust fan and a bypass route with a damper. In order to evaluate the system performance, the experiments and numerical simulations using a full-scale test house have been performed in winter or mild seasons. In the result, the ventilation rate and the heat recovery rate under the various conditions of the fan and the damper operation were clear.

Problems of heat and mass transfer optimization in the plate cross-flow heat exchangers, usedin air conditioning systems for energy recovery from exhaust air, are discussed. The mainpeculiarity of the investigated unit is the possibility of realization of heat transfer withinexhaust air canals in the dry heat exchange conditions or in the conditions of coupled heatand mass transfer with occurrence of vapour condensation on the whole or on a part of theheat exchange surface of the matrix in the form of dew or frost.

The life-cycle assessment (LCA) methodology is used in this paper to assess the environmental effects of air-handling units (AHU) over a 20-year life cycle. This assessment is based on quantifying the consumption of resources (energy and materials), the harmful emissions into the environment (air, water, and soil), and the potential changes in the environment (climate change, acidification, and ozone production).